The Surprise Mountain area is underlain by rhythmically layered amygdaloidal, feldspar porphyritic and spherulitic basalt flows of the Upper Triassic Karmutsen Formation (Vancouver Group). Mineral- ized quartz and quartz-carbonate veins with variable sulphide content are associated with narrow, steeply dipping shear zones.
The Iron Horse occurrence is underlain by amygdaloidal basalt of the Karmutsen Formation. A decline shaft is developed on a rusty weathering, 11 centimetre wide quartz vein striking 175 degrees and dipping 65 degrees west. A grab sample from the vein assayed 0.15 per cent copper and 17 grams per tonne silver (Personal Communication-EMPR, Webster, I. (1989).