Large, Active Retrogressive Thaw Slump (image) PLOS Caption This spectacular form of permafrost degradation is common in the Mackenzie Delta uplands region. Credit Joshua Thienpont Usage Restrictions All figures and photographic images will be published under a Creative Commons Attribution License (CCAL), which allows them to be freely used, distributed, and built upon as long as proper attribution is given. 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.