Mount Meager massif are covered with their eruptive products and serve as the surface expressions of intrusions. As a result, they provide a unique opportunity to study the relationships between magma chambers and their lavas. The mafic (rich in magnesium and iron), intermediate (between mafic and felsic) and felsic (rich in feldspar and quartz) volcanic rocks of the massif were erupted from at least eight volcanic vents. The Bridge River Vent is a relatively young volcanic crater that formed during an eruption about 2,400 years ago. This eruption ranged in character from explosive to effusive and involved lava dome extrusion, pyroclastic flows, lahars
Charnockite thoroughly reconstituted clays and shales. It is of wide distribution and great importance in India, Ceylon, Madagascar and Africa. It was named by geologist T. H. Holland in 1893 after the tombstone of Job Charnock, in St John's Church in Calcutta, India, which is made of this rock. The charnockite series includes rocks of many different types, some being felsic and rich in quartz and microcline, others mafic and full of pyroxene and olivine, while there are also intermediate varieties corresponding mineralogically to norites, quartz-norites and diorites. A special feature, recurring in many members of the group, is the presence