Set in the Coast Mountains, the landscape of Whistler has been carved by rivers and glaciers from a foundation of ancient metamorphic rocks 100-200 million years old. Metamorphic rocks form deep in the earth at high temperature and pressure by recrystallization and deformation of older, pre-existing rock. Continued uplift and erosion of the mountains over geologic time has brought these deeply buried rocks to the surface.

Whistler village and the ski area on Blackcomb Mountain.

Metamorphosed Granitic Rocks

Blackcomb Mountain is a ridge of metamorphosed granitic rocks. This altered and deformed quartz-rich and feldspar-rich granitic rock is much harder than the mica-rich metamorphic rocks underlying Whistler valley. These rocks have better resisted glacier and river erosion and today form rugged Blackcomb Mountain.

View of Coast Mountains from Blackcomb Mountain.

Rugged cliff: Blackcomb Mountain.

Mica-rich Metamorphic Rocks

The town of Whistler is built on strongly layered mica-rich metamorphic rocks (schist).

(Red lines indicate layering orientation)

(Red lines indicate layering orientation)

This cliff of schist fractures easily along its layering (foliation), producing an apron of flake-like fragments at the base of the cliff. Layering is due to the growth of aligned plate-like mica minerals during the metamorphism of volcanic rocks.

Through the Microscope

Microscopic view of mica-rich schist. Aligned mineral grains of muscovite (white mica) and chlorite are weakly attached, allowing fractures to form along layering. Red dotted lines indicate layering orientation.