Subglacial mound

A subglacial mound is a special kind of subglacial volcano that forms when hot lava erupts under a thick layer of ice, like a glacier or an ice sheet. The heat from the magma isn’t strong enough to break through the ice above, so it creates rocks called hyaloclastite and pillow lava deep below the surface. When the ice eventually melts away, these volcanoes are uncovered, showing a unique shape from being squeezed by the ice.

These kinds of volcanoes are not very common. They are mostly found in places that were once covered by huge sheets of ice and also had volcanic activity at the same time. You can find subglacial mounds in Iceland, Antarctica, and the Canadian province of British Columbia.

Sometimes, subglacial mounds look like cinder cones, which are another type of volcano. For example, Pyramid Mountain in the Wells Gray-Clearwater volcanic field of British Columbia was once thought to be a cinder cone, but it is actually a subglacial mound.