Tuffaceous interbeds of the Tertiary Outerson Formation; note the coarse rhyolitic rock fragments dispersed throughout (the large one in the lower portion of the photo deforms the ash layer beneath it indicating near simultaneous deposition).
Tuffaceous interbeds of the Tertiary Outerson Formation; note the coarse rhyolitic rock fragments dispersed throughout (the large one in the lower portion of the photo deforms the ash layer beneath it indicating near simultaneous deposition).