The Yamhill prospect is near the mouth of Abrahamson Creek, which flows to the northeast into Trout Lake. Its precise location is uncertain. There was some development work on the property in the early 1900s.

The Trout Lake area is underlain by a thick succession of sedimentary and volcanic rocks of the Badshot Formation and Lardeau Group near the northern end of the Kootenay arc, an arcuate, north to northwest trending belt of Paleozoic and Mesozoic strata that is now classified as a distinct, pericratonic, terrane. The arc rocks are bordered by Precambrian quartzite in the east and they young to the west, where they are bounded by Jurassic-age intrusive complexes. They were deformed during the Antler orogeny in Devonian-Mississippian time and were refolded and faulted during the Columbian orogeny, in the Middle Jurassic. A large panel, the "Selkirk allochthon", was later offset to the northeast by dip-slip motion along the Columbia River Fault.

The Badshot Formation is composed of a thick Cambrian limestone that is a distinctive marker horizon in the Trout Lake area. It is underlain by Hamill Group quartzite and it is overlain by a younger assemblage of limestone, calcareous, graphitic and siliceous argillite and siltstone, sandstone, quartzite and conglomerate, and also mafic volcanic flows, tuffs and breccias, all of which belong to the Lardeau Group. The rocks are isoclinally folded and intensely deformed, but only weakly metamorphosed. They occur as intercalated beds of marble, quartzite and grey, green and black phyllite and schist. Fyles and Eastwood (EMPR BULL 45) subdivided the group into six formations (Index, Triune, Ajax, Sharon Creek, Jowett and Broadview) of which the lowermost (Index) and uppermost (Broadview) are the most widespread. The Triune (siliceous argillite), Ajax (quartzite) and Sharon Creek (siliceous argillite) are restricted to the Trout Lake area. The Jowett is a mafic volcanic unit.

The Yamhill prospect is underlain Milford Group strata on the southwest side of Trout Lake. The rocks display a similar structural style to those of the, unconformably underlying, Lardeau Group on Silver Cup Ridge on the northeast side of the lake. They are strongly isoclinally folded and intensely sheared. However, they are closer to the Kuskanax batholith and are more strongly metamorphosed.

There is little information available on the Yamhill prospect, other than that 82.3 metres of tunneling was done on a well defined quartz vein that "carries gold and copper values" in the early 1900s. The average value of the ore was reported to be "$34/ton".