The Gang Ranch showing is located in a roadcut about five kilometres to the west of Gang Ranch. The region in which the showing occurs in underlain by mainly volcanic rocks of Eocene and Miocene ages which comprise an overlap assemblage on both Methow and Cache Creek terranes. During Miocene times diatomaceous earth formed in small synvolcanic basins. Thus, in this part of the Chilcotin Plateau there is a common association of diatomaceous earth deposits with volcanic strata.

The roadcut has exposed a Miocene lahar with clasts of both Eocene and Miocene volcanic rocks as well as clasts of diatomaceous earth. Because of poor bedrock exposure in this largely drift covered area, the source of the diatomaceous earth clasts is not known.