Pingo Formation

Pingo formation is the periglacial process that raises a dome-shaped, ice-cored mound in permafrost terrain as groundwater is forced toward the surface and freezes into a growing lens or core of pure ice, doming the overlying soil upward, sometimes to heights of tens of metres. Open-system pingos grow where groundwater is driven by artesian pressure from surrounding higher ground, while closed-system pingos grow where permafrost aggrading around a draining lake traps and freezes the water beneath it; both eventually collapse into a crater-like rampart once the ice core melts.