The sides of the small canyons are huge faults or cracks. Small amounts of basaltic lava are continuously erupting along these and other cracks in the canyon floor to fill in the gaps made by the separating plates. Where plates are separating on land, there are long canyons with faulted sides called rifts. The Kenya rift in Africa and the Rio Grande Rift in New Mexico are examples of these. In the distant past, continental crashes formed mountain ranges like the Rockies and Appalachians.
Volcanoes commonly occur along colliding plate boundaries.
In some places, like Southern California, the plates are neither colliding nor separating, but are simply sliding past each other. Unfortunately, the sliding is not smooth, but sticky and jerky. All rights reserved.