Muir Creek flows south from its headwaters on Mount Muir to the coast at Orveas Bay.
The area is underlain by basalt and basaltic pillow lavas of the Eocene Metchosin Volcanics. Metamorphic rock (slaty schists) of the Jurassic to Cretaceous Leech River Complex is exposed to the north. The Leech River Fault separates these and stretches from west of Victoria westward along the Leech River and Loss Creek valleys, reaching the coast near Sombrio Point.
Placer gold occurs almost exclusively in the gravels of the streams that drain the area that is underlain by the slaty schists of the Jurassic to Cretaceous Leech River Complex (Formation). Fairly coarse gold may be found in the gravels of virtually all these streams. The gold in recent gravel deposits is likely derived from the numerous quartz veins that occur in the slaty schists. These veins are seldom more than small stringers and lenses a few centimetres wide and approximately 1 metre in length. The only metallic minerals in the veins are a little pyrite or chalcopyrite and free gold. The veins are generally too small and too barren to be profitably mined.
The creek cuts a Tertiary canyon into Eocene Carmanah Group sedimentary rocks and Metchosin Volcanics. The gravels consist of semi-rounded boulders, from 0.3 to 1.2 metres in size, in fine sand with minor clay. The gravel is reported to be from 2.4 to 4.5 metres in depth.
It appears that most of the gold is derived from bars or in crevices in the bedrock of the river bed, or from benches along the side of the creek.
The placer deposits were discovered in the late 1800’s in association with placer gold exploration on the island, following the discovery of the Leech River Placers (MINFILE 092B 078) in the 1860’s. Minor work by local prospectors has continued through to present.
In 1928 (?), a section of creek, extending from tidewater for approximately 3.2 kilometres upstream, was prospected by J.S. Stevenson. Colours of gold were reported to be found in all pans taken while prospecting the creek.