The Great Rift
The Great Rift is a 62 mile-long system of fractures in the Earth's crust and one of the few exposed volcanic rift systems in the world and the longest rift system in the U.S.
The Rift runs northwest-to-southeast across almost the entire eastern part of the Snake River Plain. The Plain is a basalt bed several thousand feet deep, composed of numerous lava flows during the last few million years. The flows erupted from fissure or vent volcanoes located along north-south faultlines.
¤ a National Natural Landmark