Copyright © 2015 Bert N. Langford (Images may be subject to copyright. Please send feedback)
Welcome to Our Generation USA!

This Web Page Covers
Our Planet Earth,
including Earth's continents and major islands, oceans, seas and other waterways; countries, wildlife, and other inhabitants, with a footnote to visit "Environment" for Man's efforts to reverse Global Warming caused by Mankind.​ And for Human-centric topics, visit "Civilization"
For Other Planets, our Solar System and Milky Way Galaxy (and beyond), visit "THE COSMOS"

Our Planet, Earth including its History
​Pictured: "The Blue Marble" is a famous photograph of the Earth taken on December 7, 1972, by the crew of the Apollo 17 spacecraft en route to the Moon at a distance of about 29,000 kilometers (18,000 mi). It shows Africa, Antarctica, and the Arabian Peninsula. (Courtesy of NASA/Apollo 17 crew: taken by either Harrison Schmitt or Ron Evans )
Earth (otherwise known as the world, is the third planet from the Sun, the densest planet in the Solar System, the largest of the Solar System's four terrestrial planets, and the only astronomical object known to harbor life.

According to radiometric dating and other sources of evidence, Earth formed about 4.54 billion years ago. Earth gravitationally interacts with other objects in space, especially the Sun and the Moon.

During one orbit around the Sun, Earth rotates about its axis 366.26 times, creating 365.26 solar days or one sidereal year. Earth's axis of rotation is tilted 23.4° away from the perpendicular of its orbital plane, producing seasonal variations on the planet's surface within a period of one tropical year (365.24 solar days).

The Moon is the Earth's only permanent natural satellite; their gravitational interaction causes ocean tides, stabilizes the orientation of Earth's rotational axis, and gradually slows Earth's rotational rate.

​Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years.

71% of Earth's surface is covered with water. The remaining 29% is land mass—consisting of continents and islands—that together has many lakes, rivers, and other sources of water that contribute to the hydrosphere.

The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics.

Within the first billion years of Earth's history, life appeared in the oceans and began to affect the atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago.

Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive. In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all the species of life that ever lived on Earth are extinct.

Estimates of the number of species on Earth today vary widely; most species have not been described. 

Over 7.3 billion humans live on Earth and depend on its biosphere and minerals for their survival. Humanity has developed diverse societies and cultures; politically, the world is divided into about 200 sovereign states.

Click on any of the following blue hyperlinks for further amplification about Earth:
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The History of Earth ​concerns the development of the planet Earth from its formation to the present day.

Nearly all branches of natural science have contributed to the understanding of the main events of the Earth's past. The age of Earth is approximately one-third of the age of the universe. An immense amount of geological change has occurred in that time span, accompanied by the emergence of life and its subsequent evolution.

Earth formed around 4.54 billion years ago by accretion from the solar nebula.

Volcanic outgassing probably created the primordial atmosphere and then the ocean; but the atmosphere contained almost no oxygen and so would have been toxic to most modern life including humans. Much of the Earth was molten because of frequent collisions with other bodies which led to extreme volcanism.

A "giant impact" collision with a planet-sized body is thought to have been responsible for forming the Moon. Over time, the Earth cooled, causing the formation of a solid crust, and allowing liquid water to exist on the surface.

The geological time scale (GTS) clock (see graphic) depicts the larger spans of time from the beginning of the Earth as well as a chronology of some definitive events of Earth history. The Hadean Eon represents time before the reliable (fossil) record of life beginning on Earth; it began with the formation of the planet and ended at 4.0 billion years ago as defined by international convention. 

The Archean and Proterozoic eons follow; they produced the abiogenesis of life on Earth and then the evolution of early life. The succeeding eon is the Phanerozoic, which is represented by its three component eras: the Palaeozoic; the Mesozoic, which spanned the rise, reign, and climactic extinction of the huge dinosaurs; and the Cenozoic, which presented the subsequent development of dominant mammals on Earth.

Hominins, the earliest direct ancestors of the human clade, rose sometime during the latter part of the Miocene epoch; the precise time marking the first hominins is broadly debated over a current range of 13 to 4 mya. The succeeding Quaternary period is the time of recognizable humans, i.e., the genus Homo.

The earliest undisputed evidence of life on Earth dates at least from 3.5 billion years ago, during the Eoarchean Era after a geological crust started to solidify following the earlier molten  Hadean Eon. There are microbial mat fossils such as stromatolites found in 3.48 billion-year-old sandstone discovered in Western Australia.

Other early physical evidence of a biogenic substance is graphite in 3.7 billion-year-old metasedimentary rocks discovered in southwestern Greenland as well as "remains of biotic life" found in 4.1 billion-year-old rocks in Western Australia. According to one of the researchers, "If life arose relatively quickly on Earth … then it could be common in the universe."

Living forms derived from photosynthesis appeared between 3.2 and 2.4 billion years ago and began enriching the atmosphere with oxygen. Life remained mostly small and microscopic until about 580 million years ago, when complex multicellular life arose, developed over time, and culminated in the Cambrian Explosion about 541 million years ago. This event drove a rapid diversification of life forms on Earth that produced most of the major phyla known today; and it marked the end of the Proterozoic Eon and the beginning of the Cambrian Period of the Paleozoic Era.

More than 99 percent of all species, amounting to over five billion species, that ever lived on Earth are estimated to be extinct. Estimates on the number of Earth's current species range from 10 million to 14 million, of which about 1.2 million have been documented and over 86 percent have not yet been described. More recently, in May 2016, scientists reported that 1 trillion species are estimated to be on Earth currently with only one-thousandth of one percent described.

Geological change has been a constant of Earth's crust since the time of its formation, and biological change since the first appearance of life. Species continue to evolve, taking on new forms, splitting into daughter species or going extinct in the process of adapting or dying in response to ever-changing physical environments.

The process of plate tectonics continues to play a dominant role in the shaping of Earth's oceans and continents and the living species they harbor. Changes in the biosphere—now dominated by human activity—continue, in turn, to produce significant effects on the atmosphere and other systems of the Earth's surface, such as the integrity of the ozone layer, the proliferation of greenhouse gases, the conditions of productive soils and clean air and water, and others.

Click on any of the following blue hyperlinks to learn more about the History of Earth:






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​Nature and the Natural Wonders of the WorldPictured: LEFT to RIGHT: The Victoria Falls contain the largest sheet of falling water in the world in terms of area; The Aurora Borealis or Northern Lights; and the Grand Canyon
​Click here for viewing the Natural Wonders of the World.

Nature, in the broadest sense, is the natural, physical, or material world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general.

The study of nature is a large part of science. Although humans are part of nature, human activity is often understood as a separate category from other natural phenomena.

Within the various uses of the word today, "nature" often refers to geology and wildlife.

Nature can refer to the general realm of living plants and animals, and in some cases to the processes associated with inanimate objects – the way that particular types of things exist and change of their own accord, such as the weather and geology of the Earth.

It is often taken to mean the "natural environment" or wilderness–wild animals, rocks, forest, and in general those things that have not been substantially altered by human intervention, or which persist despite human intervention.

For example, manufactured objects and human interaction generally are not considered part of nature, unless qualified as, for example, "human nature" or "the whole of nature". This more traditional concept of natural things which can still be found today implies a distinction between the natural and the artificial, with the artificial being understood as that which has been brought into being by a human consciousness or a human mind.

Depending on the particular context, the term "natural" might also be distinguished from the unnatural or the supernatural.

For Amplification, click on the following hyperlinks:

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​Life on EarthPictured: Timeline of Life on Earth.
Click to set custom HTML
Life is a characteristic distinguishing physical entities having biological processes, such as signaling and self-sustaining processes, from those that do not, either because such functions have ceased, or because they never had such functions and are classified as inanimate.

Various forms of life exist, such as 
The criteria can at times be ambiguous and may or may not define viruses, viroids, or potential artificial life as living. Biology is the primary science concerned with the study of life, although many other sciences are involved.

The definition of life is controversial. The current definition is that organisms maintain homeostasis, are composed of cells, undergo metabolism, can grow, adapt to their environment, respond to stimuli, and reproduce.

However, many other biological definitions have been proposed, and there are also some borderline cases, such as viruses. 

Biophysicists have also proposed some definitions, many being based on chemical systems. There are also some living systems theories, such as the Gaia hypothesis, the idea that the Earth is alive; the former first developed by James Grier Miller.

Another one is that life is the property of ecological systems, and yet another is the complex systems biology, a branch or subfield of mathematical biology. Some other systemic definitions include the theory involving the Darwinian dynamic and the operator theory.

However, throughout history, there have been many other theories and definitions about life, such as: 
  • materialism, the belief that everything is made out of matter and that life is merely a complex form of it; 
  • hylomorphism, the belief that all things are a combination of matter and form, and the form of a living thing is its soul; 
  • spontaneous generation, the belief that life repeatedly emerge from non-life;
  • and vitalism, a discredited scientific hypothesis that living organisms possess a "life force" or "vital spark." 

Abiogenesis is the natural process of life arising from non-living matter, such as simple organic compounds.

​Life on Earth arose 3.8–4.1 billion years ago. It is widely accepted that current life on Earth descended from an RNA world, but RNA based life may not have been the first. The mechanism by which life began on Earth is unknown, although many hypotheses have been formulated, most based on the Miller–Urey experiment.

In July 2016, scientists reported identifying a set of 355 genes from the Last Universal Common Ancestor (LUCA) of all organisms living on Earth.

Since appearing, life on Earth has changed its environment on a geologic time scale. To survive in most ecosystems, life can adapt and thrive in a wide range of conditions. Some organisms, called extremophiles, can thrive in physically or geochemically extreme conditions that are detrimental to most other life on Earth. Properties common to all organisms are the need for certain core chemical elements needed for biochemical functioning. 

Aristotle was the first person to classify organisms. Later, Carl Linnaeus introduced his system of binomial nomenclature for the classification of species. Fungi was later classified as its own kingdom.

Eventually new groups of life were revealed, such as cells and microorganisms, and even non-cellular reproducing agents, such as viruses and viroids. Cells are the smallest units of life, often called the "building blocks of life."

There are two kind of cells, prokaryotic and eukaryotic. Cells consist of cytoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids. Cells reproduce through a process of cell division in which the parent cell divides into two or more daughter cells.

Though only known on Earth, many believe in the existence of extraterrestrial life. Artificial life is a computer simulation of any aspect of life, which is used to examine systems related to life. 

Death is the permanent termination of all biological functions which sustain an organism, and as such, is the end of its life. Extinction is the process by which a group of taxa, normally a species, dies out. Fossils are the preserved remains or traces of organisms.

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Structure of the Earth
* -- National Geographic
​Pictured: Earth's Interior
The interior structure of the Earth is layered in spherical shells, like an onion. These layers can be defined by their chemical and their rheological properties. Earth has an outer silicate solid crust, a highly viscous mantle, a liquid outer core that is much less viscous than the mantle, and a solid inner core.

Scientific understanding of the internal structure of the Earth is based on observations of topography and bathymetry, observations of rock in outcrop, samples brought to the surface from greater depths by volcanoes or volcanic activity, analysis of the seismic waves that pass through the Earth, measurements of the gravitational and magnetic fields of the Earth, and experiments with crystalline solids at pressures and temperatures characteristic of the Earth's deep interior.

Mass:

The force exerted by Earth's gravity can be used to calculate its mass. Astronomers can also calculate Earth's mass by observing the motion of orbiting satellites. Earth’s average density can be determined through gravitometric experiments, which have historically involved pendulums.

The mass of Earth is about 6×1024 kg.

Structure:

The structure of Earth can be defined in two ways: by mechanical properties such as rheology, or chemically. Mechanically, it can be divided into: 


Chemically, Earth can be divided into the crust, upper mantle, lower mantle, outer core, and inner core. 

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Earthquakes including Man-Induced Earthquakes as well as a List of earthquakes striking in the United States Pictured: "The San Andreas Fault Is On The Brink Of A Devastating Earthquake"*
* -Forbes Magazine  May 8, 2016 Issue
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth, resulting from the sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can be violent enough to toss people around and destroy whole cities.

The seismicity or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time.
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Earthquakes are measured using measurements from seismometers. The moment magnitude is the most common scale on which earthquakes larger than approximately 5 are reported for the entire globe.

The more numerous earthquakes smaller than magnitude 5 reported by national seismological observatories are measured mostly on the local magnitude scale, also referred to as the Richter magnitude scale.

These two scales are numerically similar over their range of validity. Magnitude 3 or lower earthquakes are mostly imperceptible or weak and magnitude 7 and over potentially cause serious damage over larger areas, depending on their depth.

The largest earthquakes in historic times have been of magnitude slightly over 9, although there is no limit to the possible magnitude. Intensity of shaking is measured on the modified Mercalli scale. The shallower an earthquake, the more damage to structures it causes, all else being equal.

At the Earth's surface, earthquakes manifest themselves by shaking and sometimes displacement of the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes can also trigger landslides, and occasionally volcanic activity.

In its most general sense, the word earthquake is used to describe any seismic event — whether natural or caused by humans — that generates seismic waves. Earthquakes are caused mostly by rupture of geological faults, but also by other events such as volcanic activity, landslides, mine blasts, and nuclear tests. An earthquake's point of initial rupture is called its focus or hypocenter. The epicenter is the point at ground level directly above the hypocenter.

​Click on any of the following blue hyperlinks for more information about earthquakes, whether natural or caused by man:









Earth Science, including its FieldsPictured: Earth Sciences making life possible include resources for LEFT: Water and RIGHT: Energy
Click here for a List of Earth Science Fields.

Earth science or geoscience is a widely embraced term for the fields of science related to the planet Earth. Earth science can be considered to be a branch of planetary science, but with a much older history.

There are both reductionist and holistic approaches to Earth sciences. The Earth sciences can include the study of geology, the lithosphere, and the large-scale structure of the Earth's interior, as well as the atmosphere, hydrosphere, and biosphere.

Typically, Earth scientists use tools from the following to build a quantitative understanding of how the Earth system works and evolves:
Fields of Science:

The following fields of science are generally categorized within Earth sciences:
Click on any of the following blue hyperlinks to learn more about Earth Science:







Natural SciencePictured: (L) North Carolina Museum of Natural Sciences; (R) Houston Museum of Natural Sciences
​Natural science is a branch of science concerned with the description, prediction, and understanding of natural phenomena, based on observational and empirical evidence. Mechanisms such as peer review and repeatability of findings are used to try to ensure the validity of scientific advances.

Natural science can be divided into two main branches: life science (or biological science) and physical science.

Physical science is further subdivided into branches, including:
These branches of natural science may be further divided into more specialized branches (also known as fields).

In Western society's analytic tradition, the empirical sciences and especially natural sciences use tools from formal sciences, such as mathematics and logic, converting information about nature into measurements which can be explained as clear statements of the "laws of nature".

The social sciences also use such methods, but rely more on qualitative research, so that they are sometimes called "soft science", whereas natural sciences, insofar as they emphasize quantifiable data produced, tested, and confirmed through the scientific method, are sometimes called "hard science".
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Modern natural science succeeded more classical approaches to natural philosophy, usually traced to ancient Greece. Galileo, Descartes, Francis Bacon, and Newton debated the benefits of using approaches which were more mathematical and more experimental in a methodical way. Still, philosophical perspectives, conjectures, and presuppositions, often overlooked, remain requisite in natural science.

Systematic data collection, including discovery science, succeeded natural history, which emerged in the 16th century by describing and classifying plants, animals, minerals, and so on. Today, "natural history" suggests observational descriptions aimed at popular audiences.

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Bodies of Water including a List by Category as well as Based on SalinityPictured: Looking east-northeast over the Columbia Bottoms at the confluence of the Missouri River (left foreground) and the Mississippi River (upper left); RIGHT: Container Ship moving through the Panama Canal
Click here for a List of the Major Bodies of Water in the World.

Click here for a List of Bodies of Water Based on the Level of Salinity.

A body of water  is any significant accumulation of water, generally on a planet's surface.

The term most often refers to oceans, seas, and lakes, but it includes smaller pools of water such as ponds, wetlands, or more rarely, puddles.

A body of water does not have to be still or contained; Rivers, streams, canals, and other geographical features where water moves from one place to another are also considered bodies of water.

Most are naturally occurring geographical features, but some are artificial. There are types that can be either. For example, most reservoirs are created by engineering dams, but some natural lakes are used as reservoirs.

Similarly, most harbors are naturally occurring bays, but some harbors have been created through construction.

Bodies of water that are navigable are known as waterways. Some bodies of water collect and move water, such as rivers and streams, and others primarily hold water, such as lakes and oceans.

Types of Water Bodies:

Note that there are some geographical features involving water that are not bodies of water, for example waterfalls, geysers and rapids.
  • Arm of the sea - also sea arm, used to describe a sea loch.
  • Arroyo (creek) - a usually dry creek bed or gulch that temporarily fills with water after a heavy rain, or seasonally. See also wadi.
  • Artificial lake or artificial pond - see reservoir or impoundment.
  • Barachois - a lagoon separated from the ocean by a sand bar.
  • Basin - see Drainage basin.
  • Bay - an area of water bordered by land on three sides, similar to, but smaller than a gulf.
  • Bayou - a slow-moving stream or a marshy lake.
  • Beck - a small stream.
  • Bight - a large and often only slightly receding bay, or a bend in any geographical feature.
  • Billabong - see Oxbow lake; a pond or still body of water created when a river changes course and some water becomes trapped. Australian.
  • Boil - see Seep
  • Brook - a small stream.
  • Burn - a small stream.
  • Canal - an artificial waterway, usually connected to (and sometimes connecting) existing lakes, rivers, or oceans.
  • Channel - the physical confine of a river, slough or ocean strait consisting of a bed and banks. See also stream bed and strait.
  • Cove - a coastal landform. Earth scientists generally use the term to describe a circular or round inlet with a narrow entrance, though colloquially the term is sometimes used to describe any sheltered bay.
  • Basin - a region of land where water from rain or snowmelt drains downhill into another body of water, such as a river, lake, or dam.
  • Creek - a small stream.
  • Creek (tidal) - an inlet of the sea, narrower than a cove.
  • Delta - the location where a river flows into an ocean, sea, estuary, lake, or reservoir.
  • Distributary or distributary channel - a stream that branches off and flows away from a main stream channel.
  • Draw - a usually dry creek bed or gulch that temporarily fills with water after a heavy rain, or seasonally. See also wadi.
  • Estuary - a semi-enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea
  • Firth - a regional term of Scotland used to denote various coastal waters, such as large sea bays, estuaries, inlets, and straits.
  • Fjord (fiord) - a submergent landform which has occurred due to glacial activity.
  • Glacier - a large collection of ice or a frozen river that moves slowly down a mountain.
  • Glacial Pothole - see Kettle
  • Gulf - a part of a lake or ocean that extends so that it is surrounded by land on three sides, similar to, but larger than a bay.
  • Headland - an area of water bordered by land on three sides.
  • Harbor - an artificial or naturally occurring body of water where ships are stored or may shelter from the ocean's weather and currents.
  • Impoundment - an artificially-created body of water, by damming a source. Often used for flood control, as a drinking water supply (reservoir), recreation, ornamentation (artificial pond), or other purpose or combination of purposes. Note that the process of creating an "impoundment" of water is itself called "impoundment."
  • Inlet - a body of water, usually seawater, which has characteristics of one or more of the following: bay, cove, estuary, firth, fjord, geo, sea loch, or sound.
  • Kettle (or kettle lake) - a shallow, sediment-filled body of water formed by retreating glaciers or draining floodwaters.
  • Kill - used in areas of Dutch influence in New York, New Jersey and other areas of the former New Netherland colony of Dutch America to describe a strait, river, or arm of the sea.
  • Lagoon - a body of comparatively shallow salt or brackish water separated from the deeper sea by a shallow or exposed sandbank, coral reef, or similar feature.
  • Lake - a body of water, usually freshwater, of relatively large size contained on a body of land.
  • Loch - a body of water such as a lake, sea inlet, firth, fjord, estuary or bay.
  • Mangrove swamp - Saline coastal habitat of mangrove trees and shrubs.
  • Marsh - a wetland featuring grasses, rushes, reeds, typhas, sedges, and other herbaceous plants (possibly with low-growing woody plants) in a context of shallow water. See also Salt marsh.
  • Mediterranean sea (oceanography) - a mostly enclosed sea that has limited exchange of deep water with outer oceans and where the water circulation is dominated by salinity and temperature differences rather than winds
  • Mere - a lake or body of water that is broad in relation to its depth.
  • Mill pond - a reservoir built to provide flowing water to a watermill
  • Moat - a deep, broad trench, either dry or filled with water, surrounding and protecting a structure, installation, or town.
  • Ocean - a major body of salty water that, in totality, covers about 71% of the Earth's surface.
  • Oxbow lake - a U-shaped lake formed when a wide meander from the mainstem of a river is cut off to create a lake.
  • Phytotelma - a small, discrete body of water held by some plants.
  • Pool - various small bodies of water such as a swimming pool, reflecting pool, pond, or puddle.
  • Pond - a body of water smaller than a lake, especially those of artificial origin.
  • Pothole - see Kettle
  • Puddle - a small accumulation of water on a surface, usually the ground.
  • Reservoir - a place to store water for various uses, especially drinking water, which can be a natural or artificial (see Lake and Impoundment above)
  • Rill - a shallow channel of running water. These can be either natural or man-made.
  • River - a natural waterway usually formed by water derived from either precipitation or glacial meltwater, and flows from higher ground to lower ground.
  • Roadstead - a place outside a harbor where a ship can lie at anchor; it is an enclosed area with an opening to the sea, narrower than a bay or gulf (often called a "roads").
  • Run - a small stream or part thereof, especially a smoothly flowing part of a stream.
  • Salt marsh - a type of marsh that is a transitional zone between land and an area, such as a slough, bay, or estuary, with salty or brackish water.
  • Sea - a large expanse of saline water connected with an ocean, or a large, usually saline, lake that lacks a natural outlet such as the Caspian Sea and the Dead Sea. In common usage, often synonymous with ocean.
  • Sea loch - a sea inlet loch.
  • Sea lough - a fjord, estuary, bay or sea inlet.
  • Seep - a body of water formed by a spring.
  • Slough - several different meanings related to wetland or aquatic features.
  • Source - the original point from which the river or stream flows. A river's source is sometimes a spring.
  • Sound - a large sea or ocean inlet larger than a bay, deeper than a bight, wider than a fjord, or it may identify a narrow sea or ocean channel between two bodies of land.
  • Spring - a point where groundwater flows out of the ground, and is thus where the aquifer surface meets the ground surface
  • Strait - a narrow channel of water that connects two larger bodies of water, and thus lies between two land masses.
  • Stream - a body of water with a detectable current, confined within a bed and banks.
  • Subglacial lake - a lake that is permanently covered by ice and whose water remains liquid by the pressure of the ice sheet and geothermal heating. They often occur under glaciers or ice caps. Lake Vostok in Antarctica is an example.
  • Swamp - a wetland that features permanent inundation of large areas of land by shallow bodies of water, generally with a substantial number of hummocks, or dry-land protrusions.
  • Tarn - a mountain lake or pool formed in a cirque excavated by a glacier.
  • Tide pool - a rocky pool adjacent to an ocean and filled with seawater.
  • Tributary or affluent - a stream or river that flows into a main stem (or parent) river or a lake.
  • Vernal pool - a shallow, natural depression in level ground, with no permanent above-ground outlet, that holds water seasonally.
  • Wadi - a usually dry creek bed or gulch that temporarily fills with water after a heavy rain, or seasonally. See also Arroyo (creek).
  • Wash - a usually dry creek bed or gulch that temporarily fills with water after a heavy rain, or seasonally. See also wadi.
  • Wetland - an environment "at the interface between truly terrestrial ecosystems and truly aquatic systems making them different from each yet highly dependent on both" (Mitsch & Gosselink, 1986),.
See also:







Waterfalls including a List by Country Pictured: Top (L) Angel Falls, Venezuela; (R) Yosemite Falls, California;
Bottom: Niagara Falls bordering New York State and Canada
Click here for a List of Waterfalls by Country.

A waterfall is a place where water flows over a vertical drop or a series of drops in the course of a stream or river. Waterfalls also occur where meltwater drops over the edge of a tabular iceberg or ice shelf.

Waterfalls are commonly formed in the upper course of a river. At these times the channel is often narrow and deep. When the river courses over resistant bedrock, erosion happens slowly, while downstream the erosion occurs more rapidly.

As the watercourse increases its velocity at the edge of the waterfall, it plucks material from the riverbed. Whirlpools created in the turbulence as well as sand and stones carried by the watercourse increase the erosion capacity. This causes the waterfall to carve deeper into the bed and to recede upstream.

Often over time, the waterfall will recede back to form a canyon or gorge downstream as it recedes upstream, and it will carve deeper into the ridge above it. The rate of retreat for a waterfall can be as high as one and half meters per year.

Often, the rock stratum just below the more resistant shelf will be of a softer type, meaning that undercutting due to splash-back will occur here to form a shallow cave-like formation known as a rock shelter under and behind the waterfall. Eventually, the outcropping, more resistant cap rock will collapse under pressure to add blocks of rock to the base of the waterfall. These blocks of rock are then broken down into smaller boulders by attrition as they collide with each other, and they also erode the base of the waterfall by abrasion, creating a deep plunge pool or gorge.

Streams become wider and shallower just above waterfalls due to flowing over the rock shelf, and there is usually a deep area just below the waterfall because of the kinetic energy of the water hitting the bottom.

Waterfalls normally form in a rocky area due to erosion. After a long period of being fully formed, the water falling off the ledge will retreat, causing a horizontal pit parallel to the waterfall wall. Eventually, as the pit grows deeper, the waterfall collapses to be replaced by a steeply sloping stretch of river bed. In addition to gradual processes such as erosion, earth movement caused by earthquakes, landslides or volcanoes can cause a differential in land heights which interfere with the natural course of a water flow, and result in waterfalls.

A river sometimes flows over a large step in the rocks that may have been formed by a fault line. Waterfalls can occur along the edge of a glacial trough, where a stream or river flowing into a glacier continues to flow into a valley after the glacier has receded or melted. The large waterfalls in Yosemite Valley are examples of this phenomenon, which is referred to as a hanging valley. Another reason hanging valleys may form is where two rivers join and one is flowing faster than the other.

Waterfalls can be grouped into ten broad classes based on the average volume of water present on the fall (which depends on both the waterfall's average flow and its height) using a logarithmic scale. Class 10 waterfalls include Niagara Falls, Paulo Afonso Falls and Khone Falls.

Classes of other well-known waterfalls include the following: 
Types of Waterfalls  including a List of waterfalls by type:
  • Ledge waterfall: Water descends vertically over a vertical cliff, maintaining partial contact with the bedrock.
    • Block/Sheet: Water descends from a relatively wide stream or river.
    • Classical: Ledge waterfalls where fall height is nearly equal to stream width, forming a vertical square shape.
    • Curtain: Ledge waterfalls which descend over a height larger than the width of falling water stream.
  • Plunge: Fast moving water descends vertically, losing complete contact with the bedrock surface. The contact is typically lost due to horizontal thrust of the water before it falls. It always starts from a narrow stream.
    • Punchbowl: Water descends in a constricted form and then spreads out in a wider pool.
  • Horsetail: Descending water maintains contact with bedrock most of the time.
    • Slide: Water glides down maintaining continuous contact.
    • Ribbon: Water descends over a long narrow strip.
    • Chute: A large quantity of water forced through a narrow, vertical passage.
    • Fan: Water spreads horizontally as it descends while remaining in contact with bedrock.
  • Cascade: Water descends a series of rock steps.
  • Tiered/Multi-step/Staircase: A series of waterfalls one after another of roughly the same size each with its own sunken plunge pool.
  • Cataract: A large, powerful waterfall.
  • Segmented: Distinctly separate flows of water form as it descends.
  • Catadupa: A cataract or waterfall, originally those of the Nile. The term catadupae refers to people inhabiting near such cataracts; there are suppositions that these people are deaf due to the constant din.
  • Frozen: Any waterfall which has some element of ice or snow.
  • Moulin: A moulin is a waterfall in a glacier

Underwater Water Falls:

It is thought that the underwater waterfall the Denmark Strait cataract is the largest waterfall by all measures with a drop of 11,500 feet or 3,500 m and a flow rate exceeding 175 million cubic feet (5.0 million cubic meters) per second, making it 350 times as voluminous as the extinct Guaíra Falls on the border of Brazil and Paraguay, which was once thought to be the most voluminous waterfall on Earth.

Examples of Famous Waterfalls: including a List of waterfalls by height and List of waterfalls by flow rate: ​
​See also:







Land including a List of the Major Continents and Islands of the World (by Population)*--Disney Cruise Line
Pictured: The World’s Major Land Masses as (TOP) Seven Continents; BOTTOM: Major Islands
Click on the following two hyperlinks for a Listing by Population of:
Land, sometimes referred to as dry land, is the solid surface of the Earth that is not permanently covered by water. The vast majority of human activity throughout history has occurred in land areas that support agriculture, habitat, and various natural resources.

Some life forms (including terrestrial plants and terrestrial animals) have developed from predecessor species that lived in bodies of water.

Areas where land meets large bodies of water are called coastal zones. The division between land and water is a fundamental concept to humans. The demarcation between land and water can vary by local jurisdiction and other factors. A maritime boundary is one example of a political demarcation.

A variety of natural boundaries exist to help clearly define where water meets land. Solid rock landforms are easier to demarcate than marshy or swampy boundaries, where there is no clear point at which the land ends and a body of water has begun. Demarcation can further vary due to tides and weather.

A continuous area of land surrounded by ocean is called a "landmass". Although it may be most often written as one word to distinguish it from the usage "land mass"—the measure of land area—it is also used as two words. Landmasses include supercontinents, continents, and islands. There are four major continuous landmasses of the Earth: 
Land, capable of being plowed and used to grow crops, is called arable land. A country or region may be referred to as the motherland, fatherland, or homeland of its people. Many countries and other places have names incorporating -land (e.g. Iceland).

"Land mass" refers to the total surface area of the land of a geographical region or country (which may include discontinuous pieces of land such as islands). It is written as two words to distinguish it from the usage "landmass", the contiguous area of land surrounded by ocean.

The Earth's total land mass is 148,939,063.133 km2 (57,505,693.767 sq mi) which is about 29.2% of its total surface. Water covers approximately 70.8% of the Earth's surface, mostly in the form of oceans and ice formations.

Click on any of the following blue hyperlinks for more about Earth Land:






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GeologyPictured: 
LEFT: Hoodoos in Bryce Canyon. These rock spires remind of melted crayons. The tall figure is also known as Thor's Hammer. The Amphitheater where these hoodoos reside is also called the Silent City;
​RIGHT: Upper Antelope Canyon near Page, Arizona. A light shaft filtering through dust into the canyon.
​(BOTH: courtesy of Smashingapps.com)
Geology is an earth science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which they change. Geology can also refer generally to the study of the solid features of any terrestrial planet (such as the geology of the Moon or Mars).

Geology gives insight into the history of the Earth by providing the primary evidence for plate tectonics, the evolutionary history of life, and past climates.

Geology is important for mineral and hydrocarbon exploration and exploitation, evaluating water resources, understanding of natural hazards, the remediation of environmental problems, and for providing insights into past climate change. Geology also plays a role in geotechnical engineering and is a major academic discipline.

Click on any of the following blue hyperlinks for more about geology:







Geography  * -- National Geographic Channel
Geography is a field of science devoted to the study of the lands, the features, the inhabitants, and the phenomena of Earth. 

Geography is an all-encompassing discipline that seeks an understanding of the Earth and its human and natural complexities—not merely where objects are, but how they have changed and come to be.

Geography is often defined in terms of the two branches of human geography and physical geography. 

The four historical traditions in geographical research are: ​
Geography has been called "the world discipline" and "the bridge between the human and the physical sciences".

Geography is a systematic study of the Earth and its features. Traditionally, geography has been associated with cartography and place names. Although many geographers are trained in toponymy and cartology, this is not their main preoccupation.

Geographers study the space and the temporal database distribution of phenomena, processes, and features as well as the interaction of humans and their environment. Because space and place affect a variety of topics, such as: 
Geography is highly interdisciplinary. The interdisciplinary nature of the geographical approach depends on an attentiveness to the relationship between physical and human phenomena and its spatial patterns.

Click on any of the following blue hyperlinks for more about Geography:








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Paleontology * - Friends Sitcom
** -- Jurassic Park Movie Franchise
Pictured:
TOP ROW: (L) Petrified Wood and (R) Petrified Forest National Park
BOTTOM ROW: (L) Partial Dinosaur Skeleton; (R) Dinosaur National Monument Park
​Paleontology or palaeontology is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene Epoch (roughly 11,700 years before present).

It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments (their paleoecology). Paleontological observations have been documented as far back as the 5th century BC. The science became established in the 18th century as a result of Georges Cuvier's work on comparative anatomy, and developed rapidly in the 19th century.

Paleontology lies on the border between biology and geology, but differs from archaeology in that it excludes the study of anatomically modern humans. It now uses techniques drawn from a wide range of sciences, including biochemistry, mathematics, and engineering.

Use of all these techniques has enabled paleontologists to discover much of the evolutionary history of life, almost all the way back to when Earth became capable of supporting life, about 3,800 million years ago. As knowledge has increased, paleontology has developed specialised sub-divisions, some of which focus on different types of fossil organisms while others study ecology and environmental history, such as ancient climates.

Body fossils and trace fossils are the principal types of evidence about ancient life, and geochemical evidence has helped to decipher the evolution of life before there were organisms large enough to leave body fossils. Estimating the dates of these remains is essential but difficult: sometimes adjacent rock layers allow radiometric dating, which provides absolute dates that are accurate to within 0.5%, but more often paleontologists have to rely on relative dating by solving the "jigsaw puzzles" of biostratigraphy.

Classifying ancient organisms is also difficult, as many do not fit well into the Linnaean taxonomy that is commonly used for classifying living organisms, and paleontologists more often use cladistics to draw up evolutionary "family trees".

The final quarter of the 20th century saw the development of molecular phylogenetics, which investigates how closely organisms are related by measuring how similar the DNA is in their genomes. Molecular phylogenetics has also been used to estimate the dates when species diverged, but there is controversy about the reliability of the molecular clock on which such estimates depend.

Click on any of the following blue hyperlinks to learn more about the science of Paleontology:






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Insects including a List of Insects Pictured:
TOP ROW: (L) Dragonfly; (C) Monarch Butterfly; (R) Mosquito
CENTER ROW: (L) Honey Bee; (C) Grasshopper; (D) Two Ants Fighting
BOTTOM ROW: Spiders as (L) Brown Recluse Spider; (C) Black Widow Spider; (L) Tarantula
Click here for a categorical listing of Insects

​Insects are a class of hexapod invertebrates within the arthropod phylum that have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed legs, compound eyes and one pair of antennae.

Insects are the most diverse group of animals on the planet, including more than a million described species and representing more than half of all known living organisms. 

The number of extant species is estimated at between six and ten million, and potentially represent over 90% of the differing animal life forms on Earth. Insects may be found in nearly all environments, although only a small number of species reside in the oceans, a habitat dominated by another arthropod group, crustaceans.

The life cycles of insects vary but most hatch from eggs. Insect growth is constrained by the inelastic exoskeleton and development involves a series of molts. The immature stages can differ from the adults in structure, habit and habitat, and can include a passive pupal stage in those groups that undergo 4-stage metamorphosis (see holometabolism).

Insects that undergo 3-stage metamorphosis lack a pupal stage and adults develop through a series of nymphal stages. The higher level relationship of the Hexapoda is unclear.

​Fossilized insects of enormous size have been found from the Paleozoic Era, including giant dragonflies with wingspans of 55 to 70 cm (22–28 in). The most diverse insect groups appear to have coevolved with flowering plants.

Adult insects typically move about by walking, flying or sometimes swimming (see § Locomotion below). As it allows for rapid yet stable movement, many insects adopt a tripedal gait in which they walk with their legs touching the ground in alternating triangles.

Insects are the only invertebrates to have evolved flight. Many insects spend at least part of their lives under water, with larval adaptations that include gills, and some adult insects are aquatic and have adaptations for swimming.

Some species, such as water striders, are capable of walking on the surface of water. Insects are mostly solitary, but some, such as certain bees, ants and termites, are social and live in large, well-organized colonies.

Some insects, such as earwigs, show maternal care, guarding their eggs and young. Insects can communicate with each other in a variety of ways. Male moths can sense the pheromones of female moths over great distances. Other species communicate with sounds: crickets stridulate, or rub their wings together, to attract a mate and repel other males. Lampyridae in the beetle order communicate with light.

Humans regard certain insects as pests, and attempt to control them using insecticides and a host of other techniques. Some insects damage crops by feeding on sap, leaves or fruits. A few parasitic species are pathogenic. Some insects perform complex ecological roles; blow-flies, for example, help consume carrion but also spread diseases.

Insect pollinators are essential to the life-cycle of many flowering plant species on which most organisms, including humans, are at least partly dependent; without them, the terrestrial portion of the biosphere (including humans) would be devastated. Many other insects are considered ecologically beneficial as predators and a few provide direct economic benefit. 

Silkworms​ and bees have been used extensively by humans for the production of silk and honey, respectively. In some cultures, people eat the larvae or adults of certain insects.

​Click on any of the following blue hyperlinks for more about Insects:
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Plants including a List of Plants by Common Name ​* -- What plants eat insects and how do they do it? See how Venus flytraps, sundews, butterworts and pitcher plants capture insects to get nutrition in a nutrient poor environment.

Pictured:
Top Row: (L) Apple Tree, (R) Four oil-giving plants
Bottom Row: (L) Corn; (C) Rainforest that generates oxygen for life; (R) Strawberry Field
Click here for a list of plants by common name.
​
Plants are mainly multicellular, predominantly photosynthetic eukaryotes of the kingdom Plantae.

The term is today generally limited to the green plants, which form an unranked clade Viridiplantae (Latin for "green plants"). This includes:
But it excludes the red and brown algae. Historically, plants formed one of two kingdoms covering all living things that were not animals, and both algae and fungi were treated as plants; however all current definitions of "plant" exclude the fungi and some algae, as well as the prokaryotes (the archaea and bacteria).

Green plants have cell walls with cellulose and obtain most of their energy from sunlight via photosynthesis by primary chloroplasts, derived from endosymbiosis with cyanobacteria. Their chloroplasts contain chlorophylls a and b, which gives them their green color.

Some plants are parasitic and have lost the ability to produce normal amounts of chlorophyll or to photosynthesize. Plants are characterized by sexual reproduction and alternation of generations, although asexual reproduction is also common.

There are about 300–315 thousand species of plants, of which the great majority, some 260–290 thousand, are seed plants (see the table below). 

Green plants provide most of the world's molecular oxygen and are the basis of most of Earth's ecologies, especially on land. Plants that produce grains, fruits and vegetables form humankind's basic foodstuffs, and have been domesticated for millennia. Plants play many roles in culture. They are used as ornaments and, until recently and in great variety, they have served as the source of most medicines and drugs. The scientific study of plants is known as botany, a branch of biology.

Click on any of the following blue hyperlinks for further information about Plants:
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Animals including a List of Animals ​Pictured Below: 
TOP 2 ROWs: Different Wildlife (See labels)
BOTTOM ROW: Flock of Migratory Birds
Click here for a List of Animals

Animals are multicellular, eukaryotic organisms of the kingdom Animalia (also called Metazoa).

The animal kingdom emerged as a basal clade within Apoikozoa as a sister of the choanoflagellates. Sponges are the most basal clade of animals. Animals are motile, meaning they can move spontaneously and independently at some point in their lives. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later in their lives. All animals are heterotrophs: they must ingest other organisms or their products for sustenance.

Most known animal phyla appeared in the fossil record as marine species during the Cambrian explosion, about 542 million years ago. Animals can be divided broadly into vertebrates and invertebrates. Vertebrates have a backbone or spine (vertebral column), and amount to less than five percent of all described animal species. They include fish, amphibians, reptiles, birds and mammals.

The remaining animals are the invertebrates, which lack a backbone. These include the following: 
The study of animals is called zoology.

Click on any of the following blue hyperlinks for more about Animals:
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MammalsPictured: An Assortment of Mammals
Mammals are any vertebrates within the class Mammalia, which are a clade of endothermic amniotes distinguished from reptiles and birds by the possession of a neocortex (a region of the brain), hair, three middle ear bones and mammary glands.

The sister group of mammals may be the extinct Haldanodon. The mammals represent the only living Synapsida, which together with the Sauropsida form the Amniota clade. The mammals consist of the Yinotheria including monotrema and the Theriiformes including the theria.

Mammals include the largest animals on the planet, the great whales, as well as some of the most intelligent, such as elephants, primates and cetaceans. The basic body type is a terrestrial quadruped, but some mammals are adapted for life at sea, in the air, in trees, underground or on two legs.

The largest group of mammals, the placentals, have a placenta, which enables the feeding of the fetus during gestation. Mammals range in size from the 30–40 mm (1.2–1.6 in) bumblebee bat to the 30-meter (98 ft) blue whale.

With the exception of the five species of monotreme (egg-laying mammals), all modern mammals give birth to live young. Most mammals, including the six most species-rich orders, belong to the placental group.

The three largest orders in number of species are:
The next three biggest orders, depending on the biological classification scheme used, are:
All female mammals nurse their young with milk, secreted from the mammary glands.

According to Mammal Species of the World, 5,416 species were known in 2006. These were grouped in 1,229 genera, 153 families and 29 orders.

In 2008 the International Union for Conservation of Nature (IUCN) completed a five-year, 1,700-scientist Global Mammal Assessment for its IUCN Red List, which counted 5,488 species.

In some classifications, extant mammals are divided into two subclasses: the Prototheria, that is, the order Monotremata; and the Theria, or the infraclasses Metatheria and Eutheria.

The marsupials constitute the crown group of the Metatheria, and include all living metatherians as well as many extinct ones; the placentals are the crown group of the Eutheria.

While mammal classification at the family level has been relatively stable, several contending classifications regarding the higher levels—subclass, infraclass and order, especially of the marsupials—appear in contemporaneous literature. Much of the changes reflect the advances of cladistic analysis and molecular genetics. Findings from molecular genetics, for example, have prompted adopting new groups, such as the Afrotheria, and abandoning traditional groups, such as the Insectivora.

The early synapsid mammalian ancestors were sphenacodont pelycosaurs, a group that produced the non-mammalian Dimetrodon. At the end of the Carboniferous period, this group diverged from the sauropsid line that led to today's reptiles and birds.

The line following the stem group Sphenacodontia split-off several diverse groups of non-mammalian synapsids—sometimes referred to as mammal-like reptiles—before giving rise to the proto-mammals (Therapsida) in the early Mesozoic era. The modern mammalian orders arose in the Paleogene and Neogene periods of the Cenozoic era, after the extinction of non-avian dinosaurs, and have been among the dominant terrestrial animal groups from 66 million years ago to the present.

In human culture, domesticated mammals played a major role in the Neolithic revolution, causing farming to replace hunting and gathering, and leading to a major restructuring of human societies with the first civilizations. They provided, and continue to provide, power for transport and agriculture, as well as various commodities such as meat, dairy products, wool, and leather.

Mammals are hunted or raced for sport, and are used as model organisms in science. Mammals have been depicted in art since Palaeolithic times, and appear in literature, film, mythology, and religion.

Click on any of the following blue hyperlinks for more about Mammals:


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List of Diseases Carried by Insects that Impact HumansPictured below: ​Insects that can infect humans with disease include LEFT: Mosquito (West Nile Disease); RIGHT Tick (Lyme Disease)

​Invertebrates are very common vectors of disease. A vector is an organism which spreads disease from one host to another. Invertebrates spread bacterial, viral and protozoan pathogens by two main mechanisms. Either via their bite, as in the case of malaria spread by mosquitoes, or via their faeces, as in the case of Chagas' Disease spread by Triatoma bugs or epidemic typhus spread by human body lice.

Many invertebrates are responsible for transmitting diseases. Mosquitoes are perhaps the best known invertebrate vector and transmit a wide range of tropical diseases including malaria, dengue fever and yellow fever.

Another large group of vectors are flies. Sandfly species transmit the disease leishmaniasis, by acting as vectors for protozoan Leishmania species, and tsetse flies transmit protozoan trypansomes (Trypanosoma brucei gambiense and Trypansoma brucei rhodesiense) which cause African Trypanosomiasis (sleeping sickness).

Ticks and lice form another large group of invertebrate vectors. The bacterium Borrelia burgdorferi, which causes Lyme Disease, is transmitted by ticks and members of the bacterial genus Rickettsia are transmitted by lice. For example, the human body louse transmits the bacterium Rickettsia prowazekii which causes epidemic typhus.

Although invertebrate-transmitted diseases pose a particular threat on the continents of Africa, Asia and South America, there is one way of controlling invertebrate-borne diseases, which is by controlling the invertebrate vector. For example, one way of controlling malaria is to control the mosquito vector through the use of mosquito nets, which prevent mosquitoes from coming into contact with humans.








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​List of Poisonous Plants
Pictured below: Recognizing the leaves of three types of poisonous plants
​Plants cannot move to escape their predators, so they must have other means of protecting themselves from herbivorous animals. Some plants have physical defenses such as thorns, spines and prickles, but by far the most common type of protection is chemical. 

Over millennia, through the process of natural selection, plants have evolved the means to produce a vast and complicated array of chemical compounds in order to deter herbivores. 

Tannin, for example, is a defensive compound that emerged relatively early in the evolutionary history of plants, while more complex molecules such as polyacetylenes are found in younger groups of plants such as the Asterales. Many of the known plant defense compounds primarily defend against consumption by insects, though other animals, including humans, that consume such plants may also experience negative effects, ranging from mild discomfort to death.

Many of these poisonous compounds also have important medicinal benefits. The varieties of phytochemical defenses in plants are so numerous that many questions about them remain unanswered, including:
  1. Which plants have which types of defense?
  2. Which herbivores, specifically, are the plants defended against?
  3. What chemical structures and mechanisms of toxicity are involved in the compounds that provide defense?
  4. What are the potential medical uses of these compounds?

These questions and others constitute an active area of research in modern botany, with important implications for understanding plant evolution and for medical science.

The link below provides an extensive, if incomplete, list of plants containing poisonous parts that pose a serious risk of illness, injury, or death to humans or animals.

There is significant overlap between plants considered poisonous and those with psychotropic properties, some of which are toxic enough to present serious health risks at recreational doses.

It is also important to remember that there is a distinction between plants that are poisonous because they naturally produce dangerous phytochemicals, and those that may become dangerous for other reasons, including but not limited to infection by bacterial, viral, or fungal parasites, the uptake of toxic compounds through contaminated soil or groundwater, and/or the ordinary processes of decay after the plant has died; this list deals exclusively with the former.

Many plants, such as peanuts, also produce compounds that are only dangerous to people who have developed an allergic reaction to them, and with a few exceptions, those plants are not included on this list (see list of allergens instead). Human fatalities caused by poisonous plants – especially resulting from accidental ingestion – are rare in the United States.

Click here for a list of poisonous plants.

Click on any of the following blue hyperlinks for more about poisonous plants:







Animal Sexual BehaviorPictured: Mating by (L) Frogs; (R) Scorpions
​Animal sexual behaviour takes many different forms, including within the same species.

Common mating or reproductively motivated systems include monogamy, polyandry, polygamy, and promiscuity.

Other sexual behavior may be reproductively motivated (e.g. sex apparently due to duress or coercion and situational sexual behaviour) or non-reproductively motivated (e.g. interspecific sexuality, sexual arousal from objects or places, sex with dead animals, homosexual sexual behaviour, bisexual sexual behavior).

When animal sexual behaviour is reproductively motivated, it is often termed mating or copulation; for most non-human mammals, mating and copulation occur at oestrus (the most fertile period in the mammalian female's reproductive cycle), which increases the chances of successful impregnation.

Some animal sexual behavior involves competition, sometimes fighting, between multiple males. Females often select males for mating only if they appear strong and able to protect themselves. The male that wins a fight may also have the chance to mate with a larger number of females and will therefore pass on his genes to their offspring.

Historically, it was believed that only humans and a small number of other species performed sexual acts other than for reproduction, and that animals' sexuality was instinctive and a simple "stimulus-response" behavior. However, in addition to homosexual behaviours, a range of species masturbate and may use objects as tools to help them do so.

Sexual behavior may be tied more strongly to establishment and maintenance of complex social bonds across a population which support its success in non-reproductive ways. Both reproductive and non-reproductive behaviours can be related to expressions of dominance over another animal or survival within a stressful situation (such as sex due to duress or coercion).

Click on any of the following blue hyperlinks for more about animal sexual behavior:
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Amphibians including a List Pictured below: four Amphibian Species
Click here for a list of Amphibians.

​Amphibians are ectothermic, tetrapod vertebrates of the class Amphibia. Modern amphibians are all Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arboreal or freshwater aquatic ecosystems.

Thus amphibians typically start out as larvae living in water, but some species have developed behavioral adaptations to bypass this. The young generally undergo metamorphosis from larva with gills to an adult air-breathing form with lungs.

Amphibians use their skin as a secondary respiratory surface and some small terrestrial salamanders and frogs lack lungs and rely entirely on their skin. They are superficially similar to lizards but, along with mammals and birds, reptiles are amniotes and do not require water bodies in which to breed.

With their complex reproductive needs and permeable skins, amphibians are often ecological indicators; in recent decades there has been a dramatic decline in amphibian populations for many species around the globe.

The earliest amphibians evolved in the Devonian period from sarcopterygian fish with lungs and bony-limbed fins, features that were helpful in adapting to dry land. They diversified and became dominant during the Carboniferous and Permian periods, but were later displaced by reptiles and other vertebrates. Over time, amphibians shrank in size and decreased in diversity, leaving only the modern subclass Lissamphibia.

The three modern orders of amphibians are Anura (the frogs and toads), Urodela (the salamanders), and Apoda (the caecilians). The number of known amphibian species is approximately 7,000, of which nearly 90% are frogs.

The smallest amphibian (and vertebrate) in the world is a frog from New Guinea (Paedophryne amauensis) with a length of just 7.7 mm (0.30 in). The largest living amphibian is the 1.8 m (5 ft 11 in) Chinese giant salamander (Andrias davidianus), but this is dwarfed by the extinct 9 m (30 ft) Prionosuchus from the middle Permian of Brazil. The study of amphibians is called batrachology, while the study of both reptiles and amphibians is called herpetology.

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Reptiles, including a List Pictured below: Clockwise from above left: Green sea turtle (Chelonia mydas), Tuatara (Sphenodon punctatus), Nile crocodile (Crocodylus niloticus), and Sinai agama (Pseudotrapelus sinaitus).(Courtesy of Petter Bøckman, CC BY-SA 3.0)
Click here for a List of Reptiles.

​Reptiles are tetrapod (four-limbed vertebrate) animals in the class Reptilia, comprising today's turtles, crocodilians, snakes, amphisbaenians, lizards, tuatara, and their extinct relatives. The study of these traditional reptile orders, historically combined with that of modern amphibians, is called herpetology.

Because some reptiles are more closely related to birds than they are to other reptiles (e.g., crocodiles are more closely related to birds than they are to lizards), the traditional groups of "reptiles" listed above do not together constitute a monophyletic grouping (or clade). For this reason, many modern scientists prefer to consider the birds part of Reptilia as well, thereby making Reptilia a monophyletic class.

The earliest known proto-reptiles originated around 312 million years ago during the Carboniferous period, having evolved from advanced reptiliomorph tetrapods that became increasingly adapted to life on dry land.

Some early examples include the lizard-like Hylonomus and Casineria. In addition to the living reptiles, there are many diverse groups that are now extinct, in some cases due to mass extinction events.

In particular, the K–Pg extinction wiped out the pterosaurs, plesiosaurs, ornithischians, and sauropods, as well as many species of theropods (e.g. tyrannosaurids and dromaeosaurids), crocodyliforms, and squamates (e.g. mosasaurids).

Modern non-avian reptiles inhabit every continent with the exception of Antarctica. (If birds are classed as reptiles, then all continents are inhabited.)

Several living subgroups are recognized: 
Reptiles are tetrapod vertebrates, creatures that either have four limbs or, like snakes, are descended from four-limbed ancestors. Unlike amphibians, reptiles do not have an aquatic larval stage.

Most reptiles are oviparous, although several species of squamates are viviparous, as were some extinct aquatic clades — the fetus develops within the mother, contained in a placenta rather than an eggshell.

As amniotes, reptile eggs are surrounded by membranes for protection and transport, which adapt them to reproduction on dry land. Many of the viviparous species feed their fetuses through various forms of placenta analogous to those of mammals, with some providing initial care for their hatchlings. 

Extant reptiles range in size from a tiny gecko, Sphaerodactylus ariasae, which can grow up to 17 mm (0.7 in) to the saltwater crocodile, Crocodylus porosus, which may reach 6 m (19.7 ft) in length and weigh over 1,000 kg (2,200 lb).

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Aquatic Animals and Marine Life ​* -- James Cameron, Director of movies "Avatar" and "Titanic", took this awesome dive down into the Mariana Trench in 2012
Pictured below: Marine Life's Natural Habitat
​An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. 

Natural environments and the animals that live in them can be categorized as aquatic (water) or terrestrial (land).

The term aquatic can in theory be applied to animals that live in either fresh water (fresh water animals) or salt water (marine animals). However, the adjective marine is most commonly used for animals that live in saltwater, i.e. in oceans, seas, etc.

Aquatic animals (especially freshwater animals) are often of special concern to conservationists because of the fragility of their environments. Aquatic animals are subject to pressure from overfishing, destructive fishing, marine pollution and climate change.

Air-breathing Aquatic Animals: In addition to water breathing animals, e.g., fishes, mollusks etc., the term "aquatic animal" can be applied to air-breathing aquatic or sea mammals such as those in the orders Cetacea (whales) and Sirenia (sea cows), which cannot survive on land, as well as to the pinnipeds (true seals, eared seals, and the walrus). The term "aquatic mammal" is also applied to four-footed mammals like the river otter (Lontra canadensis) and beavers (family Castoridae), although these are technically amphibious.

Certain fish also evolved to breathe air to survive oxygen-deprived water, such as arapaima (family Osteoglossidae) and walking catfish.
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​Marine life, or sea life or ocean life, refers to the plants, animals and other organisms that live in the salt water of the sea or ocean, or the brackish water of coastal estuaries. At a fundamental level, marine life helps determine the very nature of our planet.

Marine organisms produce much of the oxygen we breathe. Shorelines are in part shaped and protected by marine life, and some marine organisms even help create new land.

Most life forms evolved initially in marine habitats. Oceans provide about 99 percent of the living space on the planet. 

The earliest vertebrates appeared in the form of fish, which live exclusively in water. Some of these evolved into amphibians which spend portions of their lives in water and portions on land. Other fish evolved into land mammals and subsequently returned to the ocean as seals, dolphins or whales.

Plant forms such as kelp and algae grow in the water and are the basis for some underwater ecosystems. Plankton, and particularly phytoplankton, are key primary producers forming the general foundation of the ocean food chain.

Marine vertebrates must obtain oxygen to survive, and they do so in various ways. Fish have gills instead of lungs, although some species of fish, such as the lungfish, have both. 

Marine mammals, such as dolphins, whales, otters, and seals need to surface periodically to breathe air. Some amphibians are able to absorb oxygen through their skin. Invertebrates exhibit a wide range of modifications to survive in poorly oxygenated waters including breathing tubes (see insect and mollusc siphons) and gills (Carcinus). However, as invertebrate life evolved in an aquatic habitat most have little or no specialisation for respiration in water.

Altogether there are 230,000 documented marine species, and it has been estimated that nearly two million marine species are yet to be documented. Marine species range in size from the microscopic, including plankton and phytoplankton which can be as small as 0.02 micrometres, to huge cetaceans (whales, dolphins and porpoises) which in the case of the blue whale reach up to 33 metres (109 feet) in length, being the largest known animal.

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Birds, Including a List of Bird Species
YouTube Video of 19 "Funny Birds" Compilation
YouTube Video of the Scary Scene in the Alfred Hitchcock Thriller "The Birds"*​
* -- "The Birds" (1963)
Pictured: (Top Left) Ostrich, (Top Right) Hummingbird, and (Bottom) a Peacock

Click here for a List of Bird Species.

​Birds are a group of endothermic vertebrates, characterized by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton.

Birds live worldwide and range in size from the 5 cm (2 in) bee hummingbird to the 2.75 m (9 ft) ostrich. They rank as the class of tetrapods with the most living species, at approximately ten thousand, with more than half of these being passerines, sometimes known as perching birds.

The fossil record indicates that birds are the last surviving group of dinosaurs, having evolved from feathered ancestors within the theropod group of saurischian dinosaurs. True birds first appeared during the Cretaceous period, around 100 million years ago.

DNA-based evidence finds that birds diversified dramatically around the time of the Cretaceous–Palaeogene extinction event that killed off all other dinosaurs. Birds, especially those in the southern continents, survived this event and then migrated to other parts of the world while diversifying during periods of global cooling.

Primitive bird-like dinosaurs that lie outside class Aves proper, in the broader group Avialae, have been found dating back to the mid-Jurassic period.

Many of these early "stem-birds", such as Archaeopteryx, were not yet capable of fully powered flight, and many retained primitive characteristics like toothy jaws in place of beaks, and long bony tails.

Birds have wings which are more or less developed depending on the species; the only known groups without wings are the extinct moa and elephant birds. Wings, which evolved from forelimbs, gave birds the ability to fly, although further evolution has led to the loss of flight in flightless birds, including ratites, penguins, and diverse endemic island species of birds. The digestive and respiratory systems of birds are also uniquely adapted for flight.

Some bird species of aquatic environments, particularly seabirds and some waterbirds, have further evolved for swimming.

Some birds, especially corvids and parrots, are among the most intelligent animals; several bird species make and use tools, and many social species pass on knowledge across generations, which is considered a form of culture.

Many species annually migrate great distances. Birds are social, communicating with visual signals, calls, and bird songs, and participating in such social behaviours as cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of bird species are socially monogamous (referring to social living arrangement, distinct from genetic monogamy), usually for one breeding season at a time, sometimes for years, but rarely for life.

Other species have breeding systems that are polygynous (arrangement of one male with many females) or, rarely, polyandrous (arrangement of one female with many males). Birds produce offspring by laying eggs which are fertilized through sexual reproduction. They are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching. Some birds, such as hens, lay eggs even when not fertilized, though unfertilized eggs do not produce offspring.

Many species of birds are economically important. Domesticated and undomesticated birds (poultry and game) are important sources of eggs, meat, and feathers. Songbirds, parrots, and other species are popular as pets. Guano (bird excrement) is harvested for use as a fertilizer.

Birds prominently figure throughout human culture. About 120–130 species have become extinct due to human activity since the 17th century, and hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Recreational birdwatching is an important part of the ecotourism industry.

Click on any of the following blue hyperlinks for more about the Birds Species:







Volcanoes including Types of Volcanic Eruptions as well as a List of Volcanic Eruptions by Death Toll
YouTube Video of Top 10 Deadliest Volcanic Eruptions in History
Pictured: ​Illustration comparing major volcanic eruptions over the millennia

Click here for a List of volcanic eruptions by death toll


A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.

Earth's volcanoes occur because its crust is broken into 17 major, rigid tectonic plates that float on a hotter, softer layer in its mantle. Therefore, on Earth, volcanoes are generally found where tectonic plates are diverging or converging.

For example, a mid-oceanic ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates pulling apart; the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates coming together.

Volcanoes can also form where there is stretching and thinning of the crust's interior plates, e.g., in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande Rift in North America. This type of volcano falls under the umbrella of "plate hypothesis" volcanism. Volcanism away from plate boundaries has also been explained as mantle plumes. These so-called "hotspots", for example Hawaii, are postulated to arise from upwelling diapirs with magma from the core–mantle boundary, 3,000 km deep in the Earth. Volcanoes are usually not created where two tectonic plates slide past one another.

Erupting volcanoes can pose many hazards, not only in the immediate vicinity of the eruption. One such hazard is that volcanic ash can be a threat to aircraft, in particular those with jet engines where ash particles can be melted by the high operating temperature; the melted particles then adhere to the turbine blades and alter their shape, disrupting the operation of the turbine.

Large eruptions can affect temperature as ash and droplets of sulfuric acid obscure the sun and cool the Earth's lower atmosphere (or troposphere); however, they also absorb heat radiated up from the Earth, thereby warming the upper atmosphere (or stratosphere). Historically, so-called volcanic winters have caused catastrophic famines.

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Types of Volcanic Eruptions:

Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcano experts. These are often named after famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series.

There are three different types of eruptions:
  1. The most well-observed are magmatic eruptions, which involve the decompression of gas within magma that propels it forward. 
  2. Phreatomagmatic eruptions are another type of volcanic eruption, driven by the compression of gas within magma, the direct opposite of the process powering magmatic activity.
  3. The third eruptive type is the phreatic eruption, which is driven by the superheating of steam via contact with magma; these eruptive types often exhibit no magmatic release, instead causing the granulation of existing rock.

Within these wide-defining eruptive types are several subtypes. The weakest are Hawaiian and submarine, then Strombolian, followed by Vulcanian and Surtseyan.

The stronger eruptive types are Pelean eruptions, followed by Plinian eruptions; the strongest eruptions are called "Ultra-Plinian." 

Subglacial and phreatic eruptions are defined by their eruptive mechanism, and vary in strength. An important measure of eruptive strength is Volcanic Explosivity Index (VEI), an order of magnitude scale ranging from 0 to 8 that often correlates to eruptive types.

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​Gemstone including a List
YouTube Video: Comparisons of Diamond Clarity Grades
​Pictured: ​LEFT: A selection of gemstone pebbles made by tumbling rough rock with abrasive grit, in a rotating drum. The biggest pebble here is 40 mm (1.6 in) long; RIGHT: Group of precious and semiprecious stones —both uncut and faceted— including (clockwise from top left) diamond, uncut synthetic sapphire, ruby, uncut emerald, and amethyst crystal cluster.
A gemstone (also called a gem, fine gem, jewel, precious stone or semi-precious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments.

However, certain rocks (such as lapis lazuli) or organic materials that are not minerals (such as amber, jet, and pearl) are also used for jewelry and are therefore often considered to be gemstones as well.

Most gemstones are hard, but some soft minerals are used in jewelry because of their luster or other physical properties that have aesthetic value. Rarity is another characteristic that lends value to a gemstone.

Apart from jewelry, from earliest antiquity engraved gems and hardstone carvings, such as cups, were major luxury art forms. A gem maker is called a lapidary or gemcutter; a diamond worker is a diamantaire.

The carvings of Carl Fabergé are significant works in this tradition.

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Rock (Stone) including a List of Rock Types
YouTube Video: How Granite Countertops are Made
Pictured: LEFT: Balanced Rock stands in the Garden of the Gods park in Colorado Springs (Courtesy of EvanS – Own work GDFL); RIGHT: inside a marble quarry in Vermont.
Click here for a list of the many types of rocks.

Rock or stone is a natural substance, a solid aggregate of one or more minerals or mineraloids. For example, granite, a common rock, is a combination of the minerals quartz, feldspar and biotite. The Earth's outer solid layer, the lithosphere, is made of rock.

Rock has been used by mankind throughout history. The minerals and metals found in rocks have been essential to human civilization.

Three major groups of rocks are defined: igneous, sedimentary, and metamorphic. The scientific study of rocks is called petrology, which is an essential component of geology.

At a granular level, rocks are composed of grains of minerals, which, in turn, are homogeneous solids formed from a chemical compound that is arranged in an orderly manner.

The aggregate minerals forming the rock are held together by chemical bonds. The types and abundance of minerals in a rock are determined by the manner in which the rock was formed.

Many rocks contain silica (SiO2); a compound of silicon and oxygen that forms 74.3% of the Earth's crust. This material forms crystals with other compounds in the rock. The proportion of silica in rocks and minerals is a major factor in determining their name and properties.

Rocks are geologically classified according to characteristics such as mineral and chemical composition, permeability, the texture of the constituent particles, and particle size. These physical properties are the end result of the processes that formed the rocks. Over the course of time, rocks can transform from one type into another, as described by the geological model called the rock cycle.

These events produce three general classes of rock: igneous, sedimentary, and metamorphic. which are subdivided into many groups. However, there are no hard and fast boundaries between allied rocks. By increase or decrease in the proportions of their constituent minerals they pass by every gradation into one another, the distinctive structures also of one kind of rock may often be traced gradually merging into those of another.

Hence the definitions adopted in establishing rock nomenclature merely correspond to more or less arbitrary selected points in a continuously graduated series.

Human Use:

​The use of rocks has had a huge impact on the cultural and technological development of the human race. Rocks have been used by humans and other hominids for at least 2.5 million years. 

Lithic technology marks some of the oldest and continuously used technologies. The mining of rocks for their metal ore content has been one of the most important factors of human advancement, which has progressed at different rates in different places in part because of the kind of metals available from the rocks of a region.

Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or (coal) seam. This term also includes the removal of soil.

Materials recovered by mining include the following: 
Mining is required to obtain any material that cannot be grown through agricultural processes, or created artificially in a laboratory or factory.

Mining in a wider sense comprises extraction of any resource (e.g. petroleum, natural gas, salt or even water) from the earth.

Mining of rock and metals has been done since prehistoric times. Modern mining processes involve prospecting for ore bodies, analysis of the profit potential of a proposed mine, extraction of the desired materials and finally reclamation of the land to prepare it for other uses once mining ceases.

The nature of mining processes creates a potential negative impact on the environment both during the mining operations and for years after the mine has closed. This impact has led to most of the world's nations adopting regulations to manage negative effects of mining operations.

See also:






​
Giant seamount discovered in Guatemala is nearly twice the height of the world’s tallest building (CNN) (Seamount Wikipedia) Pictured below: Color-graded bathymetry of the seamount that has been discovered off the coast of Guatemala. The seamount is 1,600 meters (5,249 feet) tall.
CNN -- 12/1/2023

​The seamount was discovered 84 nautical miles outside the Guatemalan Exclusive Economic Zone. It is estimated that there are more than 100,000 seamounts taller than 1,000 meters (3,280 feet) in the world, but less than one-tenth of a percent have been explored, according to NOAA.

“Seamounts have been explored only relatively recently due to the advent of human occupied submersibles and very capable remotely operated vehicles (ROVs),” said Les Watling, an emeritus biology professor with the University of Hawaii at Manoa, via email. Watling was not involved with the discovery but was part of a Schmidt Ocean Institute exploration in 2019.

Finding a seamount“The fact that it is not on the chart is a bit amazing,” Watling said, noting that most of the ocean floor is unexplored. (NOAA estimates less than 25% of the ocean floor has been mapped as of 2023.)

Ocean researchers know where most seamounts — even ones that haven’t been mapped and explored — are in the world due to satellite radar altimeters, which are used to detect slight differences in the height of the sea by measuring the time it takes a radar pulse sent from a satellite to reach the ocean’s surface and return, Watling said. Above a seamount’s location, the surface of the ocean will bulge slightly, allowing for detection of the large underwater mountains.

​About 11 kilometers (6.8 miles) away from where the seamount was mapped, satellite altimetry had shown a modeled seamount, which was most likely this recently mapped seamount, Ketter said, since the pinpoint location of the model may be off due to other land masses in the area. The seamount was not mapped or known before, only its location was predicted from satellite data, he said.

The recently discovered seamount may be taller than the world’s tallest building, but some have been found to have a height of 4,000 meters (13,123 feet) or more, Watling said. The tallest mountain in the world, Mauna Kea in Hawaii — which measures more than 10,210 meters (33,500 feet) from base to peak — started out as a seamount, according to NOAA.

Seamounts act as biodiversity hot spotsDue to a seamount’s geological formation, the mountains tend to serve as biodiversity hot spots, providing a hard surface to which corals, sponges and other marine invertebrates can cling.

“Seamounts create distinct ecosystems because the normally sluggish currents above the deep seafloor accelerate as much as 10-fold as they flow around these obstructions,” said Tony Koslow, an emeritus research oceanographer with Scripps Institution of Oceanography at the University of California, San Diego, in an email.

The accelerated currents create the hard rock substrate to which invertebrates attach themselves while also drawing in other fauna that feed on food particles swept around by the currents, said Koslow, author of “The Silent Deep: The Discovery, Ecology, and Conservation of the Deep Sea.” He was not involved in the discovery.

​Researchers estimate that 15% to 35% of endemic ocean species live in a seamount ecosystem, and migratory species also seek out the structures to breed, feed or seek refuge, according to the Pew Charitable Trusts.

“The incredible diversity of life on seamounts has been recognized only relatively recently,” Koslow said. “Perhaps the most significant aspect of this discovery is that it confirms that the seafloor is still poorly mapped.”

[End of CNN Article]
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​Seamount (Wikipedia)

​A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface (sea level), and thus is not an island, islet, or cliff-rock.

Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from the seafloor to 1,000–4,000 m (3,300–13,100 ft) in height. They are defined by oceanographers as independent features that rise to at least 1,000 m (3,281 ft) above the seafloor, characteristically of conical form. 

The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. During their evolution over geologic time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. After they have subsided and sunk below the sea surface such flat-top seamounts are called "guyots" or "tablemounts".

Earth's oceans contain more than 14,500 identified seamounts, of which 9,951 seamounts and 283 guyots, covering a total area of 8,796,150 km2 (3,396,210 sq mi), have been mapped but only a few have been studied in detail by scientists.

Seamounts and guyots are most abundant in the North Pacific Ocean, and follow a distinctive evolutionary pattern of eruption, build-up, subsidence and erosion. In recent years, several active seamounts have been observed, for example Kamaʻehuakanaloa (formerly Lōʻihi) in the Hawaiian Islands.

Because of their abundance, seamounts are one of the most common marine ecosystems in the world. Interactions between seamounts and underwater currents, as well as their elevated position in the water, attract plankton, corals, fish, and marine mammals alike. Their aggregational effect has been noted by the commercial fishing industry, and many seamounts support extensive fisheries.

There are ongoing concerns on the negative impact of fishing on seamount ecosystems, and well-documented cases of stock decline, for example with the orange roughy (Hoplostethus atlanticus). 95% of ecological damage is done by bottom trawling, which scrapes whole ecosystems off seamounts.

Because of their large numbers, many seamounts remain to be properly studied, and even mapped. Bathymetry and satellite altimetry are two technologies working to close the gap.

There have been instances where naval vessels have collided with uncharted seamounts; for example, Muirfield Seamount is named after the ship that struck it in 1973. However, the greatest danger from seamounts are flank collapses; as they get older, extrusions seeping in the seamounts put pressure on their sides, causing landslides that have the potential to generate massive tsunamis.


Geography:

Seamounts can be found in every ocean basin in the world, distributed extremely widely both in space and in age. A seamount is technically defined as an isolated rise in elevation of 1,000 m (3,281 ft) or more from the surrounding seafloor, and with a limited summit area, of conical form. There are more than 14,500 seamounts. In addition to seamounts, there are more than 80,000 small knolls, ridges and hills less than 1,000 m in height in the world's oceans.
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Most seamounts are volcanic in origin, and thus tend to be found on oceanic crust near mid-ocean ridges, mantle plumes, and island arcs. Overall, seamount and guyot coverage is greatest as a proportion of seafloor area in the North Pacific Ocean, equal to 4.39% of that ocean region.

The Arctic Ocean has only 16 seamounts and no guyots, and the Mediterranean and Black seas together have only 23 seamounts and 2 guyots. The 9,951 seamounts which have been mapped cover an area of 8,088,550 km2 (3,123,010 sq mi).

Seamounts have an average area of 790 km2 (310 sq mi), with the smallest seamounts found in the Arctic Ocean and the Mediterranean and Black Seas; whilst the largest mean seamount size, 890 km2 (340 sq mi), occurs in the Indian Ocean. The largest seamount has an area of 15,500 km2 (6,000 sq mi) and it occurs in the North Pacific.

Guyots cover a total area of 707,600 km2 (273,200 sq mi) and have an average area of 2,500 km2 (970 sq mi), more than twice the average size of seamounts. Nearly 50% of guyot area and 42% of the number of guyots occur in the North Pacific Ocean, covering 342,070 km2 (132,070 sq mi).

The largest three guyots are all in the North Pacific: the Kuko Guyot (estimated 24,600 km2 (9,500 sq mi)), Suiko Guyot (estimated 20,220 km2 (7,810 sq mi)) and the Pallada Guyot (estimated 13,680 km2 (5,280 sq mi)).

Grouping:

"Seamount chain" redirects here. For a broader coverage of this topic, see Undersea mountain range.

Seamounts are often found in groupings or submerged archipelagos, a classic example being the Emperor Seamounts, an extension of the Hawaiian Islands. Formed millions of years ago by volcanism, they have since subsided far below sea level. This long chain of islands and seamounts extends thousands of kilometers northwest from the island of Hawaii.

There are more seamounts in the Pacific Ocean than in the Atlantic, and their distribution can be described as comprising several elongate chains of seamounts superimposed on a more or less random background distribution. 

Seamount chains occur in all three major ocean basins, with the Pacific having the most number and most extensive seamount chains. These include:
  • the Hawaiian (Emperor),
  • Mariana,
  • Gilbert,
  • Tuomotu
  • and Austral Seamounts (and island groups)
  • in the north Pacific
    • and the Louisville and Sala y Gomez ridges in the southern Pacific Ocean.

In the North Atlantic Ocean, the New England Seamounts extend from the eastern coast of the United States to the mid-ocean ridge. Craig and Sandwell noted that clusters of larger Atlantic seamounts tend to be associated with other evidence of hotspot activity, such as:
The mid-Atlantic ridge and spreading ridges in the Indian Ocean are also associated with abundant seamounts. Otherwise, seamounts tend not to form distinctive chains in the Indian and Southern Oceans, but rather their distribution appears to be more or less random.

Isolated seamounts and those without clear volcanic origins are less common; examples include: 
If all known seamounts were collected into one area, they would make a landform the size of Europe. Their overall abundance makes them one of the most common, and least understood, marine structures and biomes on Earth, a sort of exploratory frontier.


Geology:

Geochemistry and evolution:

​Most seamounts are built by one of two volcanic processes, although some, such as the Christmas Island Seamount Province near Australia, are more enigmatic. 

Volcanoes near plate boundaries and mid-ocean ridges are built by decompression melting of rock in the upper mantle. The lower density magma rises through the crust to the surface.

Volcanoes formed near or above subducting zones are created because the subducting tectonic plate adds volatiles to the overriding plate that lowers its melting point.

Which of these two process involved in the formation of a seamount has a profound effect on its eruptive materials. Lava flows from mid-ocean ridge and plate boundary seamounts are mostly basaltic (both tholeiitic and alkalic), whereas flows from subducting ridge volcanoes are mostly calc-alkaline lavas. Compared to mid-ocean ridge seamounts, subduction zone seamounts generally have more sodium, alkali, and volatile abundances, and less magnesium, resulting in more explosive, viscous eruptions.

All volcanic seamounts follow a particular pattern of growth, activity, subsidence and eventual extinction. The first stage of a seamount's evolution is its early activity, building its flanks and core up from the sea floor. This is followed by a period of intense volcanism, during which the new volcano erupts almost all (e.g. 98%) of its total magmatic volume.

The seamount may even grow above sea level to become an oceanic island (for example, the 2009 eruption of Hunga Tonga). After a period of explosive activity near the ocean surface, the eruptions slowly die away. With eruptions becoming infrequent and the seamount losing its ability to maintain itself, the volcano starts to erode.

After finally becoming extinct (possibly after a brief rejuvenated period), they are ground back down by the waves. Seamounts are built in a far more dynamic oceanic setting than their land counterparts, resulting in horizontal subsidence as the seamount moves with the tectonic plate towards a subduction zone. Here it is subducted under the plate margin and ultimately destroyed, but it may leave evidence of its passage by carving an indentation into the opposing wall of the subduction trench.

The majority of seamounts have already completed their eruptive cycle, so access to early flows by researchers is limited by late volcanic activity.

Ocean-ridge volcanoes in particular have been observed to follow a certain pattern in terms of eruptive activity, first observed with Hawaiian seamounts but now shown to be the process followed by all seamounts of the ocean-ridge type.

During the first stage the volcano erupts basalt of various types, caused by various degrees of mantle melting. In the second, most active stage of its life, ocean-ridge volcanoes erupt tholeiitic to mildly alkalic basalt as a result of a larger area melting in the mantle.

This is finally capped by alkalic flows late in its eruptive history, as the link between the seamount and its source of volcanism is cut by crustal movement. Some seamounts also experience a brief "rejuvenated" period after a hiatus of 1.5 to 10 million years, the flows of which are highly alkalic and produce many xenoliths.

In recent years, geologists have confirmed that a number of seamounts are active undersea volcanoes; two examples are Kamaʻehuakanaloa (formerly Lo‘ihi) in the Hawaiian Islands and Vailulu'u in the Manu'a Group (Samoa).

Lava types:

​​The most apparent lava flows at a seamount are the eruptive flows that cover their flanks, however igneous intrusions, in the forms of dikes and sills, are also an important part of seamount growth.

The most common type of flow is pillow lava, named so after its distinctive shape. Less common are sheet flows, which are glassy and marginal, and indicative of larger-scale flows. Volcaniclastic sedimentary rocks dominate shallow-water seamounts. They are the products of the explosive activity of seamounts that are near the water's surface, and can also form from mechanical wear of existing volcanic rock.

Structure:

Seamounts can form in a wide variety of tectonic settings, resulting in a very diverse structural bank. Seamounts come in a wide variety of structural shapes, from conical to flat-topped to complexly shaped:
Many seamounts show signs of intrusive activity, which is likely to lead to inflation, steepening of volcanic slopes, and ultimately, flank collapse. 

There are also several sub-classes of seamounts. The first are guyots, seamounts with a flat top. These tops must be 200 m (656 ft) or more below the surface of the sea; the diameters of these flat summits can be over 10 km (6.2 mi). Knolls are isolated elevation spikes measuring less than 1,000 meters (3,281 ft). Lastly, pinnacles are small pillar-like seamounts.


Ecology:

​Ecological role of seamounts:

Seamounts are exceptionally important to their biome ecologically, but their role in their environment is poorly understood. Because they project out above the surrounding sea floor, they disturb standard water flow, causing eddies and associated hydrological phenomena that ultimately result in water movement in an otherwise still ocean bottom.

Currents have been measured at up to 0.9 knots, or 48 centimeters per second. Because of this upwelling seamounts often carry above-average plankton populations, seamounts are thus centers where the fish that feed on them aggregate, in turn falling prey to further predation, making seamounts important biological hotspots.

Seamounts provide habitats and spawning grounds for these larger animals, including numerous fish. Some species, including black oreo (Allocyttus niger) and blackstripe cardinalfish (Apogon nigrofasciatus), have been shown to occur more often on seamounts than anywhere else on the ocean floor. 

Marine mammals, sharks, tuna, and cephalopods all congregate over seamounts to feed, as well as some species of seabirds when the features are particularly shallow.

Seamounts often project upwards into shallower zones more hospitable to sea life, providing habitats for marine species that are not found on or around the surrounding deeper ocean bottom. Because seamounts are isolated from each other they form "undersea islands" creating the same biogeographical interest.

As they are formed from volcanic rock, the substrate is much harder than the surrounding sedimentary deep sea floor. This causes a different type of fauna to exist than on the seafloor, and leads to a theoretically higher degree of endemism. However, recent research especially centered at Davidson Seamount suggests that seamounts may not be especially endemic, and discussions are ongoing on the effect of seamounts on endemicity.

They have, however, been confidently shown to provide a habitat to species that have difficulty surviving elsewhere.

The volcanic rocks on the slopes of seamounts are heavily populated by suspension feeders, particularly corals, which capitalize on the strong currents around the seamount to supply them with food. These coral are therefore host to numerous other organisms in a commensal relationship, for example Brittle Stars, who climb the coral to get themselves off the seafloor, helping them to catch food particles, or small zooplankton, as they drift by. This is in sharp contrast with the typical deep-sea habitat, where deposit-feeding animals rely on food they get off the ground. In tropical zones extensive coral growth results in the formation of coral atolls late in the seamount's life.

In addition soft sediments tend to accumulate on seamounts, which are typically populated by polychaetes (annelid marine worms) oligochaetes (microdrile worms), and gastropod mollusks (sea slugs). Xenophyophores have also been found. They tend to gather small particulates and thus form beds, which alters sediment deposition and creates a habitat for smaller animals. 

Many seamounts also have hydrothermal vent communities, for example Suiyo and Kamaʻehuakanaloa seamounts. This is helped by geochemical exchange between the seamounts and the ocean water.

Seamounts may thus be vital stopping points for some migratory animals, specifically whales. Some recent research indicates whales may use such features as navigational aids throughout their migration. 

For a long time it has been surmised that many pelagic animals visit seamounts as well, to gather food, but proof of this aggregating effect has been lacking. The first demonstration of this conjecture was published in 2008.

Fishing:

The effect that seamounts have on fish populations has not gone unnoticed by the commercial fishing industry. Seamounts were first extensively fished in the second half of the 20th century, due to poor management practices and increased fishing pressure seriously depleting stock numbers on the typical fishing ground, the continental shelf. Seamounts have been the site of targeted fishing since that time.

Nearly 80 species of fish and shellfish are commercially harvested from seamounts, including: 
Conservation:

​​The ecological conservation of seamounts is hurt by the simple lack of information available. Seamounts are very poorly studied, with only 350 of the estimated 100,000 seamounts in the world having received sampling, and fewer than 100 in depth. 

Much of this lack of information can be attributed to a lack of technology, and to the daunting task of reaching these underwater structures; the technology to fully explore them has only been around the last few decades.

Before consistent conservation efforts can begin, the seamounts of the world must first be mapped, a task that is still in progress.

Overfishing is a serious threat to seamount ecological welfare. There are several well-documented cases of fishery exploitation, for example the orange roughy (Hoplostethus atlanticus) off the coasts of Australia and New Zealand and the pelagic armorhead (Pseudopentaceros richardsoni) near Japan and Russia. 

The reason for this is that the fishes that are targeted over seamounts are typically long-lived, slow-growing, and slow-maturing. The problem is confounded by the dangers of trawling, which damages seamount surface communities, and the fact that many seamounts are located in international waters, making proper monitoring difficult.

Bottom trawling in particular is extremely devastating to seamount ecology, and is responsible for as much as 95% of ecological damage to seamounts.
​
Corals from seamounts are also vulnerable, as they are highly valued for making jewellery and decorative objects. Significant harvests have been produced from seamounts, often leaving coral beds depleted.
​
Individual nations are beginning to note the effect of fishing on seamounts, and the European Commission has agreed to fund the OASIS project, a detailed study of the effects of fishing on seamount communities in the North Atlantic. 

Another project working towards conservation is CenSeam, a Census of Marine Life project formed in 2005. CenSeam is intended to provide the framework needed to prioritise, integrate, expand and facilitate seamount research efforts in order to significantly reduce the unknown and build towards a global understanding of seamount ecosystems, and the roles they have in the biogeography, biodiversity, productivity and evolution of marine organisms.

Possibly the best ecologically studied seamount in the world is Davidson Seamount, with six major expeditions recording over 60,000 species observations. The contrast between the seamount and the surrounding area was well-marked. One of the primary ecological havens on the seamount is its deep sea coral garden, and many of the specimens noted were over a century old. Following the expansion of knowledge on the seamount there was extensive support to make it a marine sanctuary, a motion that was granted in 2008 as part of the Monterey Bay National Marine Sanctuary. Much of what is known about seamounts ecologically is based on observations from Davidson. Another such seamount is Bowie Seamount, which has also been declared a marine protected area by Canada for its ecological richness.


Exploration:

The study of seamounts has been hindered for a long time by the lack of technology. Although seamounts have been sampled as far back as the 19th century, their depth and position meant that the technology to explore and sample seamounts in sufficient detail did not exist until the last few decades.

Even with the right technology available, only a scant 1% of the total number have been explored, and sampling and information remains biased towards the top 500 m (1,640 ft).

New species are observed or collected and valuable information is obtained on almost every submersible dive at seamounts.
​
Before seamounts and their oceanographic impact can be fully understood, they must be mapped, a daunting task due to their sheer number. The most detailed seamount mappings are provided by multibeam echosounding (sonar), however after more than 5000 publicly held cruises, the amount of the sea floor that has been mapped remains minuscule. 

Satellite altimetry is a broader alternative, albeit not as detailed, with 13,000 catalogued seamounts; however this is still only a fraction of the total 100,000. The reason for this is that uncertainties in the technology limit recognition to features 1,500 m (4,921 ft) or larger. In the future, technological advances could allow for a larger and more detailed catalogue.

Observations from CryoSat-2 combined with data from other satellites has shown thousands of previously uncharted seamounts, with more to come as data is interpreted.


Deep-sea mining:

Seamounts are a possible future source of economically important metals. Even though the ocean makes up 70% of Earth's surface area, technological challenges have severely limited the extent of deep sea mining.

But with the constantly decreasing supply on land, some mining specialists see oceanic mining as the destined future, and seamounts stand out as candidates.

Seamounts are abundant, and all have metal resource potential because of various enrichment processes during the seamount's life. An example for epithermal gold mineralization on the seafloor is Conical Seamount, located about 8 km south of Lihir Island in Papua New Guinea.

Conical Seamount has a basal diameter of about 2.8 km and rises about 600 m above the seafloor to a water depth of 1050 m. Grab samples from its summit contain the highest gold concentrations yet reported from the modern seafloor (max. 230 g/t Au, avg. 26 g/t, n=40).
all mineral resources that are deposited upon or within seamounts, including:
However, only the first two have any potential of being targeted by mining in the next few decades.


Dangers:
​​See also: 
Some seamounts have not been mapped and thus pose a navigational danger. For instance, Muirfield Seamount is named after the ship that hit it in 1973. 

More recently, the submarine USS San Francisco ran into an uncharted seamount in 2005 at a speed of 35 knots (40.3 mph; 64.8 km/h), sustaining serious damage and killing one seaman.

One major seamount risk is that often, in the late of stages of their life, extrusions begin to seep in the seamount. This activity leads to:
  • expansion,
  • over-extension of the volcano's flanks,
  • and ultimately flank collapse,
  • leading to submarine landslides with the potential to start major tsunamis,
  • which can be among the largest natural disasters in the world.

In an illustration of the potent power of flank collapses, a summit collapse on the northern edge of Vlinder Seamount resulted in a pronounced headwall scarp and a field of debris up to 6 km (4 mi) away. A catastrophic collapse at Detroit Seamount flattened its whole structure extensively.

Lastly, in 2004, scientists found marine fossils 61 m (200 ft) up the flank of Kohala mountain in Hawaii (island). Subsidation analysis found that at the time of their deposition, this would have been 500 m (1,640 ft) up the flank of the volcano, far too high for a normal wave to reach. The date corresponded with a massive flank collapse at the nearby Mauna Loa, and it was theorized that it was a massive tsunami, generated by the landslide, that deposited the fossils.

See also:
Image Gallery of Seamounts below:
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