Polar Caves are the result of effect of the 3rd continental glacier during the Ice Ages. During the Ice Ages the temperatures became lower and the amount of rain in the north increased, therefore much of snow did not melt during summer and formed the glaciers. The ice of the northern glaciers slid south, always melting at the tip. The moving glacier pushed the debris like a snow plough, and debris was accumulated at the rim.

Polar Cave in New Hampshire is a talus cave formed by a shrinking glacier, leaving behind huge boulders that came from the north, i.e. huge boulders of rock lying on a heap do not really fit, with crevices and cracks between them. Talus caves are uncommon, especially large ones. At Polar Caves there are actually 3 caves big enough to walk through.