The Deadman Lake diatomite/volcanic ash occurrence is located on the east side of the Vidette access road, approximately 45 (air) kilometres north of Savona. The area is accessible on a good-quality gravel road which leads north from the Trans-Canada Highway approximately 7.4 kilometres west of Savona.

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 8 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 and the best exposures of the rhyolite ash sections are on the north side of Sherwood Creek (092P 093). At the Deadman Lake volcanic ash/diatomite occurrence, a roadcut 225 metres long exposes a bank of earthy light grey material overlain by brownish material (McCammon 1960, Minister of Mines Annual Report 1959, page 184). Microscopic examination (McCammon, 1960) showed the material to be mainly diatomite with only minor amounts of ash and silt.

Outcrops of what is clearly a continuous formation are present on the east side of Deadman Valley from south of the south end of Snohoosh Lake for 8 kilometres to Deadman Lake (McCammon, 1960). The lacustrine diatomite beds occur near the base of the volcanic ash section which is 112 metres thick in a measured section east of Snohoosh Lake (Geological Survey of Canada Memoir 363, page 58). The base of the Deadman River Formation ash/lake bed section is not exposed. 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).