The Cheakamus Valley basalts are part of what southwestern British Columbia formation?
Cheakamus Valley basalts:  They are part of the Garibaldi section of the Cascade Volcanic Arc and were produced during an episode of volcanic eruptions from an unknown vent. Cascade Volcanoes: The Cascade Volcanoes (also known as the Cascade Volcanic Arc or the Cascade Arc) are a number of volcanoes in a volcanic arc in western North America, extending from southwestern British Columbia through Washington and Oregon to Northern California, a distance of well over 700 mi .
Cascade Volcanoes