Pillow Lava in the Trinity Mountains
November 25, 2006
The formation of pillow lava shown above lies over a strata of volcanic ash and diatomite in the Trinity Mountains of Nevada, an area once covered by a fresh water sea, called Lake Lahontan. Pillow lava is formed when lava is extruded under water. The outer rind is created when lava hits cool water -- the rind then breaks and the process starts over. This formation is approximately 9 million years old, and the lava itself is about 5 million years old. Photo taken on April 14, 2006.