[2] Elwyn Creek is in Mount Edziza Provincial Park which lies within the traditional territory of the Tahltan people.

They occur near the base of the Mount Edziza volcanic complex where basalt of the Nido Formation overlies Tertiary leucogranite.

Thick deposits of tufa formed by the precipitation of calcite and aragonite occur at the Elwyn Hot Springs.

Their existence may be linked to a shallow hydrothermal system driven by residual magmatic heat from the recently active Desolation Lava Field about 6 km (3.7 mi) to the east.

The main intrusive rock comprising the Elwyn Creek Pluton is fine grained, slightly porphyritic leucogranite containing phenocrysts of sodic plagioclase.