The quarry at the end of the road has good exposures of Asitka Group limestone cut by feldspar porphyry dikes (Middle Jurassic?). The limestone is medium to thin bedded and partially recrystallized. The rocks here are typical of the Asitka Group limestone which elsewhere in the Fulton Lake area has yielded Late Carboniferous-Early Permian conodonts (identification by Mike Orchard, GSC). Outcrops along the road east of the quarry are dark grey chert, metasiltstone and chlorite ± sericite schists. The protolith of these rocks is probably the Late Triassic Takla Group. Further east and presumably overlying Takla rocks are less deformed lapilli tuffs and amygdaloidal flows that are probably correlative with the Early Jurassic Saddle Hill volcanics of the Hazelton Group. The age of deformation is probably early Middle Jurassic because post kinematic porphyritic dykes at Tachek Creek, approximately 9 kilometers due south of the present locality, have given 178±7 Ma K-Ar isotopic ages (Carter, 1981). Deformation is believed to be related to folding and thrusting that occurred during a Middle Jurassic contractional event that was associated with amalgamation of Stikine and Cache Creek terranes.
Looking west down Fulton Lake, the outcrops on the north and south shore are medium grained monzonite. These rocks have been mapped as part of the Topley intrusive suite but are probably Middle Jurassic in age and therefore correlative with the Spike Peak intrusive suite.