Near Marysvale, Piute County Geologic information: The Marysvale area is dominated by Tertiary igneous rocks ranging from intermediate to silicic compositions with both volcanic and plutonic representatives. The especially thick volcanic section is thought to be the result of a large stratovolcano complex and associated calderas that existed during mid-Tertiary time. One of the common units
In the Black Rock Desert, Millard County Geologic information: Approximately 2.5 million years ago (late Tertiary Period), volcanic eruptions in the Black Spring area of the Black Rock Desert in western Utah spewed out the volcanic rocks rhyolite, pumice, and obsidian. Obsidian is a dark-colored volcanic glass formed when molten lava cools quickly. It is usually
in the Vernon Hills, Tooele County A striking feature of Vernon Hills wonderstone is its intricately folded bands that create colorful designs in cream, yellow-brown, and multiple shades of maroon. Geologic information: The Vernon Hills wonderstone is a welded-vitric tuff (vitric means glassy) of rhyolitic composition. It is a volcanic rock composed predominantly of volcanic glass