The TNS12 showing area is underlain by Lower Jurassic andesitic volcanic rocks of the Hazelton Group and Upper Triassic sedimentary rocks of the Stuhini Group. These are intruded by Early Jurassic monzodiorite to gabbroic intrusions.

A "chip sample" of a narrow 0.5 metre-thick dike of mafic to ultra-mafic rock (gabbro) trending 025 degrees . Other similar dikes in the vicinity host pyrite and pyrhotite. A sample of this gabbro dike assayed 0.047 per cent nickel (Sample TH-N-12, Assessment Report 37121).

New MINFILE showings in 2019 TNS12 and TNS24 (Thunder North area), located immediately to the south of E&L deposit (104B 006), were identified through geological mapping and prospecting in the early phase of the 2017 exploration program of Metallis Resources Inc. Prospecting at higher altitudes led to the discovery of a series of mafic to ultra-mafic outcrops (gabbro) favourable as the host of magmatic nickel-copper sulphide mineralization. The assay results from selective and continuous rock chip samples were reported to be indicative of a population anomalous in nickel and magnesium. However, a single drill hole KH17-09 which tested the structurally controlled phyllic alteration and gossans in the area of new MINFILE showing TNS24 (SampleTH-N-24) did not intersect core of economic significance.

See Mount Dunn (104B 079) and King (104B 522) for details of related historical work and geological information concerning the the Kirkham/Mount Dunn property.