The features of the Mission Mountains strongly reflect work of the last few ice ages, the latest of those being just over 10,000 years ago. But the range is also the product of a much longer story, one that can be started with the breakup of the Pangaea super-continent. As the continents began to spread out, the North American Plate inched westward, grinding over and against the Pacific Plate as it went. This subduction of the Pacific Plate caused the rise of the Rocky Mountains and thereby the Missions.