From Halfmoon Pass I hiked down to the Wheeler Geologic Area. The Wheeler Geologic Area is a highly eroded rock formation composed of layers of compacted volcanic ash that resulted from the eruptions of the La Garita Caldera approximately 25 million years ago. The caldera erupted with one of the largest known explosions in the history of the earth. The eruption is thought to have covered a significant portion of Colorado with ash. The caldera constitutes the extinct remains of a super volcano. The outcropping at the Wheeler Geologic Area is eroded into a festival of fantasy shapes.