Rhyolite Roadcut, Mt. Washburn
A road cut near Dunraven Pass, exposing a rhyolite conglomerate, provides an excellent opportunity for a small exercise in relative dating. The clasts of the clast-supported conglomerate showed little rounding. A basalt dike cut through the conglomerate, proving that it was the younger of the rock units. Finally, movement on a small fault offset both the rhyolite and the basalt, making this event more recent than the rhyolite deposition and basalt intrusion.
