Cliff exposures of Mio-Pliocene basin-fill sediments near Salida, CO

Cliff exposures of Mio-Pliocene basin-fill sediments of the Dry Union Formation along the northern front of Poncha mountain block near Salida, Colorado. An angular unconformity, visible near top of large cliff to right, separates tilted lower Dry Union gray sediments from flat-lying upper Dry Union tan gravels that are also visible in sunlit cliff cliff to left. A fault drops down the cliff sediments on the left relative to those on the right. Such relations indicate the area has been tectonically active during late stages of rifting.