The great grey cliffs of Stawamus Chief Mountain, locally known as "the Chief", are famous landmarks in the Squamish area. Rock climbers from around the world test their abilities on its vertical granite walls. Granitic rocks are ancient pools of melted rock that crystallized to rock kilometres below the surface. Tremendous uplift of the land coupled with continuous erosion over millions of years has brought these deeply buried rocks to the surface.

The Chief rises over 600 metres above Highway 99 at Squamish. Its great vertical faces result from glacial erosion along fractures in the granite.

Most climbing routes on the Chief follow fractures in the granite. Granite is favoured by rock climbers for its strong, secure holds. The rough surface of granite, created by variable weathering of its coarse minerals, provides additional grip for climbers.

From Highway 99, the Black Dyke, several metres wide, is visible on the granite face. The Black Dyke formed by intrusion of melted rock (magma) along an ancient fracture. The dyke is basalt, a fine-grained rock that breaks easily, making it a poor climbing rock. Geologists estimate the granite and dyke to be 95 and 30 million years old respectively. The dyke may have been a conduit for magma rising to an overlying volcano, long since eroded away.

Through the Microscope

Granite is composed of intergrown crystals of the minerals feldspar, quartz and amphibole that formed during the slow cooling of molten rock deep in the earth. This false-colour image uses polarized light that turns amphibole crystals into bright colours.