The Thor Odin showing area is located just south of Peters Lake, about 70 kilometres northeast of Cherryville.

The area is underlain by metamorphic rocks of the Thor Odin gneiss dome of the Proterozoic Monashee Complex and the Proterozoic to Paleozoic Kootenay Assemblage. The rocks exposed in the Thor Odin dome are separated from other strata largely by faults. The Thor Odin dome consists of a core zone comprised of migmatized biotite- aluminosilicate-rich schists and amphibolite. Overlying the core gneisses of the Thor Odin dome is an autochthonous mantling succession which consists of paragneiss, schist, quartzite, marble, calc-silicate schist and amphibolite.

In this area a distinctive aluminosilicate-rich schist is exposed. The schist is characterized by coarse porphyroblastic garnets up to 3 centimetres in diameter and/or very coarse sillimanite aggregates, up to 10 centimetres long. Sillimanite in these schists can comprise up to at least 15 per cent of the rock and is commonly rimmed by cordierite and corundum. These mafic schist layers are relatively thin, generally in the order of a few metres, but may be traced for nearly 2 kilometres along strike.

In the Mount Odin-Mount Symonds-Mount Fosthall area paragneisses and schists are present which contain abundant coarse garnet and prismatic sillimanite. Typical exposures occur along the southern branch of Ledge Creek. These gneisses and schists may contain up to 15 per cent sillimanite which is present in the form of prismatic crystals up to 10 centimetres long, and abundant garnet porphyroblasts, up to 2.5 centimetres in size (Abraham, 1967; Geological Survey of Canada Bulletin 195). In the same area, coarse garnet, 1 to 2 centimetres in size can comprise up to 30 per cent of some amphibolite layers, but more commonly is present in quantities of 10 per cent or less (Geological Survey of Canada Bulletin 195).