Arctic Thaw Slump (image) University of Alaska Fairbanks Share Print E-Mail Caption A large retrogressive thaw slump on the Noatak river; the top of the slump is ~900 feet above river water level. Retrogressive thaw slumps are caused by thawing of ice-rich permafrost and subsequent melting of ground ice on slopes. The National Park Service is currently monitoring 19 active retrogressive thaw slumps in Noatak National Preserve and Gates of the Arctic National Park and Preserve. Extrapolating the growth rate of these retrogressive thaw slumps back in time suggests that these slumps started in the late 1990s or early 2000s. Credit Photo by Rory Nichols Usage Restrictions University of Alaska Fairbanks Marketing and Communications makes high-resolution photographs available to the news media for non-commercial uses only. All uses are for one-time, non-exclusive use in one publication or production only. Credit will be given to the photographer or organization whose name is provided. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.