Wild Horse Mesa
Wild Horse Mesa Tuff and Hole-in-the-Wall:
About 17.8 million years ago, a powerful eruption blasted outward from a volcanic center in the Woods Mountains in the Eastern Mojave. Propelled by the force of rapidly rising and expanding superheated gases, a ground-hugging cloud of ash and rock fragments spread out at near-supersonic speed across the countryside. Hot, suffocating ash buried shallow lakes and stands of trees. The remains of birds, mammals, and plants are preserved as fossils in the sediments below the ash layer. The May 18, 1980 lateral blast from Mount St. Helens was somewhat analogous. The deposits from three closely spaced, violent eruptions comprise the rock unit called the Wild Horse Mesa Tuff which forms the cliffs of Hole-in-the-Wall.
Woods Mountain Caldera:
Local volcanism in the Woods Mountains area began about 17.8 million years ago, viscous siliceous magma approached the surface of the volcano. A plume of ash was spewed high into the atmosphere. Then the volcano exploded with devastating force. Two similar explosive cycles followed within less than 100,000 years. The resulting deposits formed a flat plateau extending from the Pinto Mountains to Blind Hills and from Wildhorse Mesa to the Hackberry Mountains. Such a large volume of Wild Horse Mesa Tuff was ejected from the volcano's magma chamber that overlying strata collapsed downward, forming a cone-shaped depression called a caldera. The Woods Mountains caldera, the most well preserved caldera in the Mojave, was 10 kilometers wide and 4 kilometers deep. It was largely in-filled with collapsed tuff and younger light-colored (rhyolite) flows.
source- usgs
Ecology
Providence Mountains - Lanfair ValleyNative Culture
ChemehueviAlso see:
Hole-in-the-Wall
