When a Continental plate collides with an Oceanic plate, the oceanic plate is subducted under the Continental plate and into the Mantle, this is called subduction zone.Subduction zone along an Ocenic-Continental boundary create a deep-sea trenchs along the edge of a continent. Many trenches occur around the margin of the Pacific ocean because of subduction. High temperatures cause rock to melt around the oceanic plate as it diverts under the Continental plate. The newly formed magma is forced upward through the upper mantle, causing it to form volcanoes. Subduction is responsible for most of the volcanoes and mountain ranges of British Columbia.