At the Great Central Lake occurrence, a flat-lying mass of Pennsylvanian to Permian limestone of the Buttle Lake Group, Azure Lake Formation (formerly the Buttle Lake Formation) outcrops near the southern end of the Buttle Lake uplift. Two parallel limestone bands, each up to 500 metres wide, occur on either side of a hill located 3 kilometres northwest of the west end of Great Central Lake, 48 kilometres southwest of Comox.

The two bands trend northward for 1.8 kilometres. They are separated by an overlying 750 metre wide mass of basalt of the Upper Triassic Vancouver Group, Karmutsen Formation that forms the top of the hill. This sequence is truncated to the south and north by several west trending faults. The sequence is bounded by granodiorite and quartz diorite of the Jurassic Island Intrusions to the west, east and north. The limestone and basalt lie adjacent to volcanic breccia, tuff and argillite to the south.

The geological interpretation of the uplift has recently undergone revision and the stratigraphy has been reassigned to several new formations of a redefined Sicker Group and a new Buttle Lake Group (formerly the upper part of the Sicker Group), (Juras, 1987; Massey, N. Personal Communication, 1990). See Cream 1,3 nomenclature.