Sample of welded Resting Springs Pass tuff (a welded ignimbrite) from Shoshone, California. The RSPT is about 9.5 million years old and erupted from a caldera about 50 miles to the north. It is exposed in a dramatic roadcut along CA HWY 178, east of Shoshone. Many geology fieldtrips stop there (e.g., https://woostergeologists.scotblogs.wooster.edu/2011/03/18/a-favorite-stop-the-resting-spring-tuff-exposure/) to examine the spectacular layering. This sample comes from the pink layers immediately above the black (vitrophyre) layer.
Prepared and uploaded by Trevor Byers, finished by Graham Andrews.