Antarctica’s Hidden Mountains Revealed
Antarctica has been covered with ice for thousands of years, and only recently have we been able to fully identify its underlying features. Scientists have turned the spotlight on the topography of Antarctica, and revealed much detail about its rough and rocky surface. Antarctica is actually a mountainous land, and some of the most impressive work establishing this fact has been sponsored by the British Antarctic Survey.
In collaboration with international institutes, in 2012 the BAS released a precise topological map showing the mountain ranges, valleys and plains of the Antarctic continent in stark and never-before-seen detail. This representation is called BEDMAP and it was compiled primarily through the use of radar images and satellite readings, combined with map-making software that allows for vivid recreations of the rugged Antarctic landscape.
A decade before the BAS team unveiled its map, Charles Webb from NASA’s Cryosphere Science Research Center had created a fairly detailed representation of Antarctica’s rock bed. However, his work was based only on ground-based measurements and was therefore limited in terms of how much land it could cover.
Many people had formed their impressions about Antarctica’s hidden landscape based on exposure to a copy of the Piri Reis Map, which some believe survived from extreme antiquity and accurately described Antarctica the way it was before it was covered by ice.
The Piri Reis map’s inclusion of Antarctica is especially impressive, considering it was created before Antarctica was officially discovered. The Piri Reis map was found in 1929 and dated to 1513, when it was sketched by a Turkish cartographer who apparently had access to secret information not known to the general public. It must be acknowledged that the Piri Reis map doesn’t recreate the underlying features of Antarctica perfectly, but it gets enough right to seem like more than a lucky guess.
What the techniques of modern science have revealed is that Antarctica is a land of broad and awe-inspiring geologic variety. Its most prominent mountain range, the Transantarctic Mountains in the western half of Antarctica, is about 3,500 kilometres long and features the highest mountain on the continent (Vinson Massif, at 4,850 metres). In the central part of the continent, the Gamburtsev Mountains are 1,200-1,300 kilometres long and includes peaks that rise to nearly 3,400 metres.
At the other extreme, the steepest valley on the continent is the Bentley Trench, which plunges to a depth of 2,550 metres. Long, deep canyons, troughs and valleys are common beneath the ice, adding texture to a rugged landscape that has in essence been frozen in time for millions of years.
As of now only about one percent of the rock bed of Antarctica is visible above the ice. Despite their extreme length and height, the Gamburtsev Mountains are completely buried under more than 600 metres of accumulated ice and snow.
The Gamburtsev region is actually where the deep freezing of Antarctica began 34 million years ago, when a cooling effect subsumed the continent under eight million square kilometres of hard, impenetrable ice pack. Because of its ancient origins the ice on the bottom of this pack would be among the oldest ice found anywhere on the planet, and Chinese scientists working in Antarctica have been striving for a decade to develop a drill powerful enough to reach it.
A collection of ice core samples extending to such depths, featuring perfectly preserved atmospheric samples from lost eras, would offer researchers a unique opportunity to study the evolution of Earth’s atmosphere and the changes in its climate over the course of geological time.
The Making of a Frozen Continent
The creation of present-day Antarctica occurred in two stages. First, there was the breakup of a super-continent called Gondwana, which incorporated the lands we know today as India, Africa, South America, Arabia, Australia and Antarctica. This separation may have begun as long as 250-300 million years ago, with the final division of the various continents occurring approximately 80 million years ago.
As Gondwana broke up the new continent of Antarctica began its slow migration further southward. At this time it was a lush, green land mass heavily populated with plants and animals. Rivers ran freely across broad, flat plains, although plate movements were beginning to create significant alterations in the land that would culminate in the creation of new valleys and mountain ranges.
Antarctica during this time period was verdant but highly active geologically, which would help shape the continent’s rock bed into what it is today. For example, when Antarctica began to separate from its sister continents, the movements of these enormous masses along fault lines are believed to be responsible for the creation of the Gamburtsev Mountain range in central area of the continent. Such movements are referred to as rifting, and they are known to carve out deep rift valleys and occasionally cause mountain ranges to form in the gaps between those valleys (the Gamburtsevs are flanked by rift valleys on both sides).
It should be noted that up until about 50 million years ago Earth’s climate was far warmer than it is now. Atmospheric concentrations of carbon dioxide were much higher, which caused temperatures to remain mild even near the poles. As a result Antarctica stayed green for a while even after it reached its present location on the South Pole.
Following the breakup of Gondwana, the next phase of Antarctica’s evolution occurred about 40-50 million years later, or 34 million years ago from now.
Starting around 49 million B.C, , high carbon dioxide levels in the atmosphere spurred the rapid development of a water-born fern called Azolla. Like all plant life Azolla ferns absorbed carbon dioxide from the atmosphere during the process of photosynthesis. But Azolla blooms spread so fast and were such prodigious eaters of CO2 that their presence led to dramatic decreases in atmospheric concentrations of this vital greenhouse gas. When Azolla plants expired they would sink to the bottom of seas and lakes, carrying carbon with them and removing it from circulation permanently.
By 34 million years ago, the Earth’s climate had cooled profoundly as a result of this activity, meaning it was no longer possible for a landmass located at the south pole to remain ice-free. Antarctica got colder and colder and lost its capacity to support life. Glacial ice sheets soon began their relentless march across the land, gradually turning it into the quintessential frozen wasteland we see today.
Antarctica’s Future is the Planet’s Future
Analysis of the Antarctic landscape has continued, and maps of its underlying rock bed have been refined to include the discovery of new features. But the map created by the British Antarctic Survey in 2012 continues to be the standard against which all other mapping efforts are measured.
As explained by BAS scientist and spokesperson Hamish Pritchard, efforts to reveal all the geological characteristics of the Earth’s most mysterious continent has a serious purpose beyond curiosity. The ultimate goal of the initial BAS mapping project was to find out how thick Antarctica’s ice cover is and to determine how its rock bed might influence the future movements and behaviour of that ice (or its liquid remnants, should large-scale melting begin).
“This is information that underpins the models we now use to work out how the ice flows across the continent,” Pritchard explains. “The Antarctic ice sheet is constantly supplied by falling snow, and ice flows down to the coast where great bergs calve into the ocean or it melts. To model that process requires knowledge of some complex ice physics but also of the bed topography over which the ice is flowing—and that’s BEDMAP.”
In response to global warming, the ice cap of Antarctica is shrinking. Sea levels will rise as melting continues, and as this process picks up steam its impact on the rest of the planet could be catastrophic.
How ice and water flows over and off the Antarctic continent will help determine the pace of sea level increases, should global temperatures continue to rise and the melting of the Antarctic ice cap continue. The more scientists know about what lies underneath the ice of Antarctica, the more accurately they’ll be able to predict outcomes related to climate change.
If all the ice on the West Antarctic and East Antarctic ice sheets were to melt, or simply break off from the continent and fall into the ocean, it could raise the sea level globally by as much as 64 metres. Even if only some of the ice melts, runaway global warming could flood cities and disrupt life on coastal areas all across the Earth. Therefore scientists need as much accurate data about Antarctica as they can acquire, and that’s why the data obtained by the British Antarctic Survey’s mapping project is so useful.
By Nathan Falde