antarctica has some important features hidden by the ice. one is lake vostok, which has been covered by ice for at least 15 million years. the lake is 250 km long and 50 km wide. another is the huge gamburtsev mountain chain, which are the size of the alps, yet entirely buried under the ice. the gamburtsev range has a nearby massive rift valley similar to the east african great rift valley. it is called the lambert system. scientists used radar that can work under ice to survey the whole of antarctica.