Antarctica: The Melting Continent

Antarctica: The Melting Continent — page 5 — Chapter 1 THE UNKNOWN LAND Today Antarctica is Earth’s most inhospitable continent the coldest and driest place on the planet Only a handful of plant and animal species survive here But Antarctica used to be different Not cold Not isolated Not a deathtrap The remains of dinosaurs have been unearthed in Antarctica since the At one time Antarctica was ice free and covered instead in wait for it dinosaurs 1960s and are still being discovered today The oldest among them lived during the early Triassic period 250 to 245 million years ago these were the same species of dinosaur as those found on other continents because in early dinosaur times pieces of Antarctica were joined to other pieces of land to form much larger continents than those we have today Later species were particular to Antarctica showing that Antarctica had separated from the other continents by this time causing those later dinosaurs to adapt to the now unique environment These included relatives of Brachiosaurus and Titanosaurus but unlike the giant examples found in other parts of the world the Antarctic species were as small as retriever dogs In early dinosaur times and before Antarctica wasn’t even here at the very bottom of the world All of Earth’s continents ride atop plates that make up the planet’s outer layer called its crust and are constantly moving These plates glide over molten rock heated by energy from the center of Earth This motion is incredibly slow at its quickest it’s about as fast as your fingernails grow As the plates move 8 THE UNKNOWN LAND

Antarctica: The Melting Continent — page 6 — continents crash into each other new lands are created and other land sinks under the water Today Antarctica is made up of West Antarctica and East Antarctica And how each of them ended up at the bottom of the world is a different story East Antarctica was once part of a large continent called Gondwana as were Africa India Australia and South America But Gondwana began to break up around 200 million years ago and the part that became East Antarctica eventually became more solid stable and frozen than the land that makes up West Antarctica today Among its secrets is a buried mountain range the Gamburtsev Mountains hidden under the East Antarctic ice sheet During the Jurassic period 180 million years ago the middle of dinosaur times the movement of the continents pushed East Antarctica south Eventually over the next 100 million years it shifted to its current position over the South Pole As East Antarctica moved south it slid over another plate and where the crust sank lava bubbled up in volcanoes This formed both the Andes Mountain range that runs the length of South America and the Antarctic Peninsula the long arm extending northward West Antarctica developed later in the Cretaceous period the end of the dinosaur times around 100 5 million years ago when shards of an uplifting plate split into pieces You can see those same forces are still at work today in active volcanoes including Mount Erebus which towers smoldering over Antarctic research stations that edge the Ross Sea West Antarctica crunched together at the bottom of the world a channel of ocean broke through the thinning strip of land that still connected the Antarctic Peninsula to the southern tip of South America and formed the Drake Passage Now Antarctica was separated from the other continents and a current of cold water known as the Antarctic Circumpolar Current formed a ring around it forever cutting Antarctica off from warmer seas In just 20 million years Antarctica froze As the massive pieces of Antarctica’s puzzle East and Late Jurassic period 150 million years ago Laurasia Gondwana East Antarctica Late Cretaceous period 90 million years ago Asia Africa West America East Antarctica Antarctica Quaternary period Present day Antarctica South America Drake Passage Antarctic Peninsula What Motion The motion of plates known as plate tectonics is ongoing Millions of years in the future the shapes and sizes of Earth’s continents will have changed again THE UNKNOWN LAND 9

Antarctica: The Melting Continent — page 7 — Mountains of Land Under Mountains of Ice Antarctica may be covered in ice today but beneath most of it is solid ground In some places the underlying rock stays hidden under massive glaciers in others it breaks through as towering mountains Elsewhere the ice presses out from the shore and over the ocean in huge sheets directly above the water Between East and West Antarctica loom the 2,000 mile 3,220 km Transantarctic Mountain range which looks like peaks peeking out of the snow but are really a towering range almost the height of the Rocky Mountains in North America The Antarctic Peninsula extends into the Southern Ocean It is over 620 miles 1,000 km across the Drake Passage from its tip to the closest point in South America Tierra del Fuego in Chile West TRANSANTARCTIC MOUNTAINS ANTARCTICA Antarctica’s average elevation is 8,200 feet 2,500 m making it the highest continent The highest point above sea level on the icecap is in East Antarctica at 13,428 feet 4,093 m The highest mountain where rock breaks through the ice is Mount Vinson at 16,050 feet 4,892 m Mount Erebus is the most active volcano in Antarctica Inside its crater is a glowing lake of lava 10 THE UNKNOWN LAND

Antarctica: The Melting Continent — page 8 — East West The East Antarctic Ice Sheet and West Antarctic Ice Sheet are the two biggest ice sheets in the world The thickest point of the East Antarctic Ice Sheet which is the larger of the two is nearly 3 miles 4,776 m thick over fifty times as tall as the Statue of Liberty EAST ANTARCTICA The South Pole is at the most southern point on Earth in the middle of Antarctica What’s the Antarctic low point An enormous crater 300 miles 482 km wide which lies 1 mile 1 6 km under Wilkes Land part of the East Antarctic Ice Sheet It was created by an asteroid estimated to have smashed into Earth 250 million years ago The crater is twice the size of the one created by the Chicxulub asteroid that’s thought to have wiped out the non avian dinosaurs the ones not related to birds 65 million years ago LAKE VOSTOK ANTARCTIC LOW POINT ICE VOCABULARY Bergy bits broken up icebergs brash ice floating chunks of ice up to 6 ft 6 in 2 m wide that form when other bits of ice break up calving the breaking away of a giant chunk of ice from the edge of a glacier firn dense granular ice that forms as snow ages and compresses as the air is squeezed out of it frazil soft ice that forms in turbulent water glacier a river of moving ice formed over many years as falling snow compresses growlers small icebergs or big blocks of ice that float underwater and pose an invisible danger to boats ice sheet a huge permanent layer of ice covering land ice shelf a floating sheet of ice attached to land iceberg a chunk of glacier that calves off and gets carried out to sea nilas thick sludgy ice that forms as salt water freezes pack ice an expanse of sea ice made up of lots of smaller pieces that drift because of wind or water pancake ice disks of ice that form when wind blows through sludgy ice Most of Antarctica may be covered in ice and snow but the driest spots on Earth are also found here The McMurdo Dry Valleys receive less than 3 9 inches 100 mm of precipitation per year 11 THE UNKNOWN LAND

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