The Pleistocene Huckleberry Ridge Tuff is from one of the large caldera-forming eruptions in the Yellowstone area, Central Rocky Mountains . The tuff is also visible on the skyline in the distance. At this spot (Golden Gate), the caldera erupting this was 20 km away. This eruption 2.1 Ma was followed by 2 more great caldera eruptions, the last 600,000 years ago.