A Single Emperor Penguin (Aptenodytes forsteri) stands vigil on the McMurdo Ice Shelf at the base of the erupting Mount Erebus Volcano. Feb. 25, 2009. Erebus Volcano, at 12,280 ft (3,743 m) high, is one of Earth's loftiest active volcanoes. It was discovered in 1841 by the British explorer James C. Ross. With 98% of its surface covered with ice it is hard to remember there is a rock underneath all of those tons of frozen ancient water. Mount Erebus erupts about ten times per year and even though it is encased in thick ice a molten red lava lake lies inside its summit crater. Its sides are layered with both glacial ice and old lava flows like a layercake. Strange ice formations are built over fumaroles towering some 1,000 feet tall. Erebus is strange in that its bottom half is a shield volcano and its top half a stratovolcano.