This geologic basement is at most 15 km deep with faulted sections shifted up to approximately 10 km in depth.

These are predominantly doleritic rocks with subordinate metabasic volcanics and interleaved/faulted sections of hornfelsed slates.

Ice-wedge casts transecting folded and faulted sections in the area are indisputable evidence of subsequent permafrost conditions, i.e. a period when mean annual air temperatures lay below −6 °C.