composed primarily of permafrost hummock soil frost-formed hummock 2019-01-31T19:11:58Z 2019-01-31T19:17:20Z A hummock which is primarily composed of soil that has been pushed up by frost action. Permafrost hummocks are often found in uniformly spaced large groups. Hummocks can form in areas of permafrost or seasonally frozen ground, and are one of the most common surface features of the Arctic. hummock envoPolar frost heave