A mass of limestone of the Middle to Upper Permian Marble Canyon Formation (Cache Creek Group) outcrops along the Springhouse Hills, just north of Alkali Lake, 70 kilometres west-northwest of 100 Mile House. The mass trends northward for 18 kilometres with widths of up to 10 kilometres. The unit is underlain by a sequence of chert, argillite and greywacke with minor basalt of the Mississippian to Triassic Cache Creek Group. Bedding dips vertically to steeply northwest to southwest.