The Sherwood Creek volcanic ash occurrence is located on the north side of Sherwood Creek, east of Snohoosh Lake in the Deadman River valley. The area is accessible on a good-quality gravel road north from the Trans-Canada Highway, 7.4 kilometres west of Savona, 40 (air) kilometres to the south.
Basalts of the Miocene Chasm Formation (Chilcotin Group) mantle most of the area, however, beneath the basalts, massive rhyolite ash of the Miocene Deadman River Formation (Chilcotin Group) is exposed in cliffs on the east side of the Deadman Valley for a length of 6.5 kilometres. The rhyolite ash is the predominant lithology in a Miocene channel filling of fluviatile and lacustrine sediments occupying the northwest trending Mio-Snohoosh Channel (Open File 1989-21). The flat-lying channel is more than 200 metres in thickness. The best exposures of the rhyolite ash sections are on the north side of Sherwood Creek. At Sherwood Creek, the lowest exposed beds are buff to grey ash followed by a 3 metre thick bed of chalky white ash, then 30 metres of buff to yellow beds overlain by 2 metres of white ash topped by mixed buff beds. The white beds are uniform very fine ash.
One kilometre south of Sherwood Creek, on the east side of the road, ash is exposed along a length of 120 metres in a 20-metre cliff. At the north end of Skookum Lake, 4 kilometres north of Sherwood Creek, cliffs of ash are again exposed east of the road. Several less well-exposed outcrops of what is clearly a continuous formation are present from south of the south end of Snohoosh Lake to Skookum Lake (McCammon 1960, Minister of Mines Annual Report 1959, page 181).
The occurrence has been known for many years and sporadic attempts have been made to exploit it. Prior to 1927, approximately 1 ton (900 kilograms) was removed. It was later staked by T.C. McAlpine and examined in 1959 by C. Riley for Industrial Minerals Limited, a private company. Preliminary estimates suggested the size of the deposit at approximately 14 million tonnes. McCammon (1960) tested the ash for pozzolanic properties. This work indicates that it meets ASTM specifications, and could be used as a pozzolan. It also has possibilities as a cream glaze on ceramic ware (McCammon, 1960) or as an abrasive (Eardley-Wilmot, 1927). Michael Dickens (Assessment reports 22221 and 22546) staked claims in the area in 1991 and submitted samples for chemical analyses which showed the ash to be composed of approximately 35 percent montmorillonite clay. He also undertook experiments which demonstrated that the material was an effective absorbent which effectively absorbed oil spills and offensive odours.