<P> East Antarctica is geologically varied, dating from the Precambrian era, with some rocks formed more than 3 billion years ago . It is composed of a metamorphic and igneous platform which is the basis of the continental shield . On top of this base are coal and various modern rocks, such as sandstones, limestones and shales laid down during the Devonian and Jurassic periods to form the Transantarctic Mountains . In coastal areas such as Shackleton Range and Victoria Land some faulting has occurred . </P> <P> The main mineral resource known on the continent is coal . It was first recorded near the Beardmore Glacier by Frank Wild on the Nimrod Expedition, and now low - grade coal is known across many parts of the Transantarctic Mountains . The Prince Charles Mountains contain significant deposits of iron ore . The most valuable resources of Antarctica lie offshore, namely the oil and natural gas fields found in the Ross Sea in 1973 . Exploitation of all mineral resources is banned until 2048 by the Protocol on Environmental Protection to the Antarctic Treaty . </P> <P> Antarctica is the coldest of Earth's continents . It used to be ice - free until about 34 million years ago, when it became covered with ice . The coldest natural air temperature ever recorded on Earth was − 89.2 ° C (− 128.6 ° F) at the Soviet (now Russian) Vostok Station in Antarctica on 21 July 1983 . For comparison, this is 10.7 ° C (20 ° F) colder than subliming dry ice at one atmosphere of partial pressure, but since CO only makes up 0.039% of air, temperatures of less than − 140 ° C (− 220 ° F) would be needed to produce dry ice snow in Antarctica . A lower air temperature of − 94.7 ° C (− 138.5 ° F) was recorded in 2010 by satellite--however, it may be influenced by ground temperatures and was not recorded at a height of 7 feet above the surface as required for the official air temperature records . Antarctica is a frozen desert with little precipitation; the South Pole itself receives less than 10 cm (4 in) per year, on average . Temperatures reach a minimum of between − 80 ° C (− 112 ° F) and − 89.2 ° C (− 128.6 ° F) in the interior in winter and reach a maximum of between 5 ° C (41 ° F) and 15 ° C (59 ° F) near the coast in summer . Sunburn is often a health issue as the snow surface reflects almost all of the ultraviolet light falling on it . Given the latitude, long periods of constant darkness or constant sunlight create climates unfamiliar to human beings in much of the rest of the world . </P> <P> East Antarctica is colder than its western counterpart because of its higher elevation . Weather fronts rarely penetrate far into the continent, leaving the centre cold and dry . Despite the lack of precipitation over the central portion of the continent, ice there lasts for extended periods . Heavy snowfalls are common on the coastal portion of the continent, where snowfalls of up to 1.22 metres (48 in) in 48 hours have been recorded . </P>

When was the last date antarctica was free of ice