hummock

A small, rounded mound or hillock — in tundra and permafrost terrain, a frost-heaved dome of soil covered with grass or moss, one of hundreds or thousands in a field of identical bumps called hummock tundra. In swamps, a hummock is a raised island of vegetation above the waterline. In ice, a hummock is a mound of broken, refrozen sea ice pushed up by pressure. Three landscapes, one shape: a bump in a flat world.