Geological history and paleontology

More than 170 million years ago, Antarctica was part of the supercontinent

Supercontinent

In geology, a supercontinent is a landmass comprising more than one continental core, or craton. The assembly of cratons and accreted terranes that form Eurasia qualifies as a supercontinent today.-History:...

 Gondwana

Gondwana

In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...

. Over time Gondwana broke apart and Antarctica as we know it today was formed around 25 million years ago.

Paleozoic era (540–250 Ma)

During the Cambrian

Cambrian

The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...

 period, Gondwana had a mild climate. West Antarctica was partially in the northern hemisphere, and during this period large amounts of sandstone

Sandstone

Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...

s, limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

s and shale

Shale

Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...

s were deposited. East Antarctica was at the equator, where sea-floor invertebrate

Invertebrate

An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...

s and trilobite

Trilobite

Trilobites are a well-known fossil group of extinct marine arthropods that form the class Trilobita. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period , and they flourished throughout the lower Paleozoic era before...

s flourished in the tropical seas. By the start of the Devonian period (416 Ma) Gondwana was in more southern latitudes and the climate was cooler, though fossils of land plants are known from this time. Sand

Sand

Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...

 and silt

Silt

Silt is granular material of a size somewhere between sand and clay whose mineral origin is quartz and feldspar. Silt may occur as a soil or as suspended sediment in a surface water body...

s were laid down in what is now the Ellsworth

Ellsworth Mountains

The Ellsworth Mountains are the highest mountain ranges in Antarctica, forming a long and wide chain of mountains in a north to south configuration on the western margin of the Ronne Ice Shelf. They are bisected by Minnesota Glacier to form the northern Sentinel Range and the southern Heritage...

, Horlick

Horlick Mountains

The Horlick Mountains are a mountain range in the Transantarctic Mountains of Antarctica, lying eastward of Reedy Glacier and including the Wisconsin Range, Long Hills and Ohio Range....

 and Pensacola Mountains

Pensacola Mountains

The Pensacola Mountains are a large group of mountain ranges and peaks in Antarctica, extending 450 km in a NE-SW direction, comprising the Argentina Range, Forrestal Range, Dufek Massif, Cordiner Peaks, Neptune Range, Patuxent Range, Rambo Nunataks and Pecora Escarpment...

. Glaciation began at the end of the Devonian period (360 Ma) as Gondwana became centered around the South Pole

South Pole

The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is one of the two points where the Earth's axis of rotation intersects its surface. It is the southernmost point on the surface of the Earth and lies on the opposite side of the Earth from the North Pole...

 and the climate cooled, though flora remained. During the Permian period the plant life became dominated by fern-like plants such as Glossopteris

Glossopteris

Glossopteris is the largest and best-known genus of the extinct order of seed ferns known as Glossopteridales ....

, which grew in swamps. Over time these swamps became deposits of coal in the Transantarctic Mountains

Transantarctic Mountains

The three largest mountain ranges on the Antarctic continent are the Transantarctic Mountains , the West Antarctica Ranges, and the East Antarctica Ranges. The Transantarctic Mountains compose a mountain range in Antarctica which extend, with some interruptions, across the continent from Cape Adare...

. Towards the end of the Permian period continued warming led to a dry, hot climate over much of Gondwana.

Mesozoic era (250–65 Ma)

As a result of continued warming, the polar ice caps melted and much of Gondwana became a desert. In East Antarctica the seed fern became established, and large amounts of sandstone and shale were laid down at this time. The Antarctic Peninsula began to form during the Jurassic period (206–146 Ma), and islands gradually rose out of the ocean. Ginkgo

Ginkgo

Ginkgo , also spelled gingko and known as the Maidenhair Tree, is a unique species of tree with no close living relatives...

 trees and cycad

Cycad

Cycads are seed plants typically characterized by a stout and woody trunk with a crown of large, hard and stiff, evergreen leaves. They usually have pinnate leaves. The individual plants are either all male or all female . Cycads vary in size from having a trunk that is only a few centimeters...

s were plentiful during this period, as were reptiles such as Lystrosaurus

Lystrosaurus

Lystrosaurus was a genus of Late Permian and Early Triassic Period dicynodont therapsids, which lived around 250 million years ago in what is now Antarctica, India, and South Africa...

. In West Antarctica conifer forest

Forest

A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...

s dominated through the entire Cretaceous period (146–65 Ma), though Southern beech

Nothofagus

Nothofagus, also known as the southern beeches, is a genus of 35 species of trees and shrubs native to the temperate oceanic to tropical Southern Hemisphere in southern South America and Australasia...

 began to take over at the end of this period. Ammonite

Ammonite

Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct subclass within the Molluscan class Cephalopoda which are more closely related to living coleoids Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct...

s were common in the seas around Antarctica, and dinosaurs were also present, though only three Antarctic dinosaur genera (in order of naming, Cryolophosaurus

Cryolophosaurus

Cryolophosaurus was a large theropod dinosaur, with a crest on its head that looked like a Spanish comb. Due to the resemblance of this feature to Elvis Presley's pompadour haircut from the 1950s, this dinosaur was at one point informally known as "Elvisaurus".Cryolophosaurus was excavated from...

, Antarctopelta

Antarctopelta

Antarctopelta was a genus of ankylosaurian dinosaur with one known species, A. oliveroi, which lived in Antarctica during the Late Cretaceous Period. It was a medium-sized ankylosaur, reaching no more than 4 meters in length, and showed characteristics of two different families, making more...

, and Glacialisaurus

Glacialisaurus

Glacialisaurus is a genus of massospondylid sauropodomorph dinosaur. It lived during the Early Jurassic period in what is now central Transantarctic Mountains of Antarctica. It is known from the holotype FMNH PR1823, a partial hind limb and from the referred material FMNH PR1822, a left...

) have been described to date. It was during this period that Gondwana began to break up.

Geology of present-day Antarctica

The geological study of Antarctica has been greatly hindered by the fact that nearly all of the continent is continuously covered with a thick layer of ice. However, new techniques such as remote sensing

Remote sensing

Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth by means of propagated signals Remote sensing...

 have begun to reveal the structures beneath the ice.

Geologically, West Antarctica closely resembles the Andes

Andes

The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...

 of South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

. The Antarctic Peninsula

Antarctic Peninsula

The Antarctic Peninsula is the northernmost part of the mainland of Antarctica. It extends from a line between Cape Adams and a point on the mainland south of Eklund Islands....

 was formed by uplift and metamorphism

Metamorphism

Metamorphism is the solid-state recrystallization of pre-existing rocks due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids. Mineralogical, chemical and crystallographic changes can occur during this process...

 of sea-bed sediments during the late Paleozoic

Paleozoic

The Paleozoic era is the earliest of three geologic eras of the Phanerozoic eon, spanning from roughly...

 and the early Mesozoic

Mesozoic

The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...

 eras. This sediment uplift was accompanied by igneous intrusions and volcanism

Volcanism

Volcanism is the phenomenon connected with volcanoes and volcanic activity. It includes all phenomena resulting from and causing magma within the crust or mantle of a planet to rise through the crust and form volcanic rocks on the surface....

. The most common rocks in West Antarctica are andesite

Andesite

Andesite is an extrusive igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture. In a general sense, it is the intermediate type between basalt and dacite. The mineral assemblage is typically dominated by plagioclase plus pyroxene and/or hornblende. Magnetite,...

 and rhyolite

Rhyolite

This page is about a volcanic rock. For the ghost town see Rhyolite, Nevada, and for the satellite system, see Rhyolite/Aquacade.Rhyolite is an igneous, volcanic rock, of felsic composition . It may have any texture from glassy to aphanitic to porphyritic...

 volcanics formed during the Jurassic Period. There is also evidence of volcanic activity, even after the ice sheet had formed, in Marie Byrd Land

Marie Byrd Land

Marie Byrd Land is the portion of West Antarctica lying east of the Ross Ice Shelf and the Ross Sea and south of the Pacific Ocean, extending eastward approximately to a line between the head of the Ross Ice Shelf and Eights Coast. It stretches between 158°W and 103°24'W...

 and Alexander Island

Alexander Island

Alexander Island or Alexander I Island or Alexander I Land or Alexander Land is the largest island of Antarctica, with an area of lying in the Bellingshausen Sea west of the base of the Antarctic Peninsula, from which it is separated by Marguerite Bay and George VI Sound. Alexander Island lies off...

. The only anomalous area of West Antarctica is the Ellsworth Mountains

Ellsworth Mountains

The Ellsworth Mountains are the highest mountain ranges in Antarctica, forming a long and wide chain of mountains in a north to south configuration on the western margin of the Ronne Ice Shelf. They are bisected by Minnesota Glacier to form the northern Sentinel Range and the southern Heritage...

 region, where the stratigraphy

Stratigraphy

Stratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....

 is more similar to the eastern part of the continent.

The West Antarctic Rift

West Antarctic Rift

The West Antarctic Rift is a major, active rift valley lying between East and West Antarctica. It encompasses the Ross Sea, the area under the Ross Ice Shelf and a part of West Antarctica...

, a major active rift valley

Rift valley

A rift valley is a linear-shaped lowland between highlands or mountain ranges created by the action of a geologic rift or fault. This action is manifest as crustal extension, a spreading apart of the surface which is subsequently further deepened by the forces of erosion...

, lies between West and East Antarctica. The rift is still active with slow movement of West Antarctica away from East Antarctica.

East Antarctica is geologically very old, dating from the Precambrian

Precambrian

The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...

 era, with some rocks formed more than 3 billion years ago. It is composed of a metamorphic

Metamorphic rock

Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...

 and igneous platform which is the basis of the continental shield

Shield (geology)

A shield is generally a large area of exposed Precambrian crystalline igneous and high-grade metamorphic rocks that form tectonically stable areas. In all cases, the age of these rocks is greater than 570 million years and sometimes dates back 2 to 3.5 billion years...

. On top of this base are various more modern rocks, such as sandstone

Sandstone

Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...

s, limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

s, coal and shale

Shale

Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...

s laid down during the Devonian and Jurassic periods to form the Transantarctic Mountains

Transantarctic Mountains

The three largest mountain ranges on the Antarctic continent are the Transantarctic Mountains , the West Antarctica Ranges, and the East Antarctica Ranges. The Transantarctic Mountains compose a mountain range in Antarctica which extend, with some interruptions, across the continent from Cape Adare...

. In coastal areas such as Shackleton Range

Shackleton Range

The Shackleton Range is a mountain range in Antarctica. Rising to , it extends in an east-west direction for about between the Slessor and Recovery glaciers....

 and Victoria Land

Victoria Land

Victoria Land is a region of Antarctica bounded on the east by the Ross Ice Shelf and the Ross Sea and on the west by Oates Land and Wilkes Land. It was discovered by Captain James Clark Ross in January 1841 and named after the UK's Queen Victoria...

 some faulting has occurred.

The main mineral

Mineral

A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...

 resource known on the continent is coal

Coal

Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

. It was first recorded near the Beardmore Glacier

Beardmore Glacier

The Beardmore Glacier in Antarctica is one of the largest glaciers in the world, with a length exceeding 160 km . The glacier is one of the main passages from the Ross Ice Shelf through the Queen Alexandra and Commonwealth ranges of the Transantarctic Mountains to the Antarctic Plateau, and was one...

 by Frank Wild

Frank Wild

Commander John Robert Francis Wild CBE, RNVR, FRGS , known as Frank Wild, was an explorer...

 on the Nimrod Expedition

Nimrod Expedition

The British Antarctic Expedition 1907–09, otherwise known as the Nimrod Expedition, was the first of three expeditions to the Antarctic led by Ernest Shackleton. Its main target, among a range of geographical and scientific objectives, was to be first to the South Pole...

, and now low-grade coal is known across many parts of the Transantarctic Mountains. The Prince Charles Mountains

Prince Charles Mountains

Prince Charles Mountains is a major group of mountains in Mac. Robertson Land in Antarctica, including the Athos Range, the Porthos Range, and the Aramis Range. The highest peak is Mount Menzies . Other prominent peaks are Mount Izabelle and Mount Stinear...

 contain significant deposits of iron ore. The most valuable resources of Antarctica lie offshore, namely the oil

Oil field

An oil field is a region with an abundance of oil wells extracting petroleum from below ground. Because the oil reservoirs typically extend over a large area, possibly several hundred kilometres across, full exploitation entails multiple wells scattered across the area...

 and natural gas field

Natural gas field

Oil and natural gas are produced by the same geological process according fossil fuel suggestion: anaerobic decay of organic matter deep under the Earth's surface. As a consequence, oil and natural gas are often found together...

s found in the Ross Sea

Ross Sea

The Ross Sea is a deep bay of the Southern Ocean in Antarctica between Victoria Land and Marie Byrd Land.-Description:The Ross Sea was discovered by James Ross in 1841. In the west of the Ross Sea is Ross Island with the Mt. Erebus volcano, in the east Roosevelt Island. The southern part is covered...

 in 1973. Exploitation of all mineral resources by signatory states is banned until 2048 by the Protocol on Environmental Protection to the Antarctic Treaty

Protocol on Environmental Protection to the Antarctic Treaty

The Protocol on Environmental Protection to the Antarctic Treaty, also known as the Antarctic-Environmental Protocol, or the Madrid Protocol, is part of the Antarctic Treaty System...

.