The Similkameen Coal prospect is on the west bank of the Similkameen River, 6 kilometres southwest of Princeton.

This coal deposit is situated in the south-central part of the Princeton Basin, a northerly trending fault-bounded trough filled by Eocene volcanic rocks of mainly intermediate composition, comprising the Lower Volcanic Formation, and an overlying Eocene sedimentary sequence of sandstone, shale, waterlain rhyolite tephra (tuff) and coal, up to 2000 metres thick, comprising the Allenby Formation.

The deposit may correlate with the Pleasant Valley-Jackson coal zone, one of four significant coal-bearing zones in a 530-metre section in the Allenby Formation (Princeton Group) (Geological Survey of Canada Paper 52-12, page 22).

A coal seam, 1.3 metres thick, is exposed in the river bank. The seam contains one thin bentonite band and 1.19 metres of clean coal (Geological Survey of Canada Paper 52-12, Figure 2, section 7). It is overlain by 1.8 metres of bentonite and underlain by 0.5 metre of clay or shale.

A second seam occurs in an adit 130 metres southwest of the river bank exposure. The seam is up to 1.22 metres thick and is overlain by sandy shale and underlain by shaly coal (Paper 1983-3, Figure 13B, section 6).