Between 3,000 and 1,500 years ago during the late Holocene epoch, the Belknap shield volcano as well as the Belknap Crater cone and Little Belknap shield volcano erupted, generating lava flows that spread throughout the McKenzie Pass area. Belknap Crater's lava flows were produced from its northeastern base and extended to the west, reaching the McKenzie River valley. These events represent one of the largest periods of recent volcanism in the Cascade Range, and were comparable in terms of effusion rates to the formation of Mount Bachelor.