Ross Island is an island lying on the east side of McMurdo Sound and extending 43 miles from Cape Bird on the North to Cape Armitage on the South, and a like distance from Cape Royds on the West to Cape Crozier on the east. This island is entirely volcanic, Mount Erebus, 3,795 meters, near the center, being an active volcano; and Mount Terror, 3,230 meters, about 20 miles eastward, being an extinct volcano. Mount Bird rises to 1,765 meters just South of Cape Bird. This area was discovered by Sir James Clark Ross in 1841, but he thought it formed part of the mainland of Victoria Land. Determined to be an island and named by the BrNAE (1901-04) for Sir James Clark Ross.