The Waterfall occurrence area is situated along the Nahlin fault which dips steeply to the northeast. The Upper Mississippian to Permian Nahlin ultramafic body of Cache Creek Complex, comprised of peridotite and serpentinized peridotite, lies to the north of the fault. The Lower Jurassic Inklin Formation (Laberge Group) lies to the south of the Nahlin fault and comprises a thick sequence of sedimentary rocks predominantly shale and siltstone. Tertiary quartz-feldspar porphyry stocks and dikes related to the Sloko-Hyder Plutonic Suite intrude the Inklin sedimentary rocks. These intrusions appear to be concentrated along the Nahlin fault zone.
Clay alteration within the intrusions is variable, where intense, the rocks are soft and weather white. The porphyry is medium-grained and massive, and hosts disseminated pyrite throughout the stock and in small quartz veins within the stock. Felsite and quartz-feldspar porphyry dykes and sills, probably related to the stock, are also clay altered and contain disseminated pyrite. Contact metamorphic effects are locally evident as narrow biotite hornfels zones and pyritic zones in the Inklin sedimentary rocks.
Gossanous rocks are extensively altered quartz-feldspar porphyry. They consist of limonite, clay minerals, and chlorite.
Mineralization of the quartz-feldspar porphyry consists of disseminated pyrite. Quartz-calcite stringers in the porphyry contain trace amounts of sphalerite and galena. Arsenopyrite blebs are associated with a fine-grained, hornblende andesite dyke in Nickel Creek. A massive sulphide vein up to 15 centimetres thick is exposed in Nickel Creek at the waterfall. The sulphide vein cuts Inklin sedimentary rocks and consists primarily of pyrite, sphalerite, and chalcopyrite. Silicified Inklin rocks locally contain abundant disseminated pyrite in small altered zones.
Prospecting indicated silver and silver-gold geochemical anamolies associated in altered Inklin sedimentary rocks adjacent to the Nahlin fault and close to the quartz-feldspar porphyry intrusions. In 1982, a sample taken from a gossanous zone in the altered porphyry assayed 30.0 grams per tonne silver and 0.27 grams per tonne gold. These values are thought to be associated with small, thin quartz-sphalerite stringers in the porphyry intrusive (Assessment Report 10701).
Also in 1982, stibnite needles were observed on fracture faces within the Inklin sediments exposed on the north side of Yeth Creek.
In 1981, Chevron Minerals Ltd. staked the Goat claims to cover a Geological Survey of Canada nickel showing. In 1982 Chevron conducted geological mapping and sampling which lead to the discovery of a massive sulphide vein (104K 067) and gold-silver bearing argillic zones in the intrusive rocks.
In 1989, Tahltan Holdings Ltd collected a total of 10 heavy mineral samples and 22 rock samples and conducted a mapping program on their Yeth claim.
In 2005, geological field reconnaissance mapping and rock sampling (29 samples) was carried on the Fall property, consisting of eight claims in the northern part of the Kizmet project area, a joint venture between Barrick Gold Inc and Rimfire Minerals Corporation. The Fall claims covered the Waterfall (104K 067), Ho (104K 111) and Goat (104K 046) showings. No samples were taken at the Goat during the program. Of the 29 rock samples collected on the Fall property, only a few yielded anomalous results (Assessment Report 28090). One grab sample taken near the Waterfall showing contained blebs of pyrite and veinlets likely to be sphalerite and yielded 6.1 grams per tonne silver. A float sample collected near the Waterfall showing yielded 3.3 grams per tonne silver and 0.2 per cent zinc. One float sample taken near the Ho showing yielded 1.3 grams per tonne silver.
