Yedomas show one ice age by Michael J. Oard Just recently, another indicator of just one ice age has emerged. Yedomas are a special type of permafrost that contain a large amount of organic matter (about 2% carbon by mass) and from 50 to 80% ice by volume.17 The ice is in the form of large ice wedges and ice layers and lenses. Permafrost covers 23 million km2, or 24%, of land in the Northern Hemisphere. Yedomas cover substantially less—1,387,000 km2 in north-east Siberia, Alaska, and Yukon Territory of north-west Canada.18 They are often tens of metres thick with a...