Geological Survey Bulletin 104 The Glaciation of the Yellowstone Valley North of the Park

The region herein discussed is a mountainous tract lying immediately north of the Yellowstone National Park, and drained by the Boulder and the Yellowstone rivers and many lesser tributary streams. The Yellowstone, rising far to the south, is here a noble stream of beryl green water which is joined by the Gardiner as it leaves the border of the park and flows northward through Cinnabar valley into a narrow gorge cut in Archean gneisses. From this canyon it darts out into a broad mountain flanked valley that is 30 miles long and from 3 to 6 miles wide, fancifully christened "Paradise valley," which it leaves through the lower canyon, or gate of the mountains, a narrow cut in the steeply upturned and folded Paleozoic rocks, to emerge into the great terraced valley that is the beginning of its long course through the Cretaceous rocks. The Boulder river, on the other hand, is a much smaller stream that heads in the snow banks about Haystack peak, and joined by numerous mountain torrents from the neighboring summits flows northward through a narrow canyon with walls 3,000 feet high, to join the Yellowstone in its great terraced valley about Big Timber.