Mount Shannon, east of Chilliwack, is mapped by Monger as Lower and Middle Jurassic Harrison Lake Formation rock which consists of intermediate to locally felsic flows and pyroclastics, with local argillite and conglomerate (GSC Map 41-1989). Minister of Mines Annual Reports from 1955 to 1959 report a quarry on Mount Shannon, but include it, however, under the "Granite" quarry section. No description of the type of rock is mentioned in the reports. About 34,500 tonnes of rock, used for dike repair, was produced over three years in the late 1950s, and the quarry was in operation at least one more year but production was not reported.