yedoma
A type of Pleistocene-age (formed 1.8 million to 10,000 years before present) permafrost that contains a significant amount of organic material with ice content of 50 to 90 percent by volume. Thawing yedoma is a significant source of atmospheric methane.
Image
A yedoma in Russia shows the thick layer of ice and carbon material exposed along this body of water.
Vladimir Romanovsky
Topic(s):
frozen ground or permafrost