Cloud Peak Wilderness: The Last Unglaciated Terrain in Wyoming

The Bighorn Mountains rise abruptly out of the Wyoming plains, a flat-topped uplift that reaches thirteen thousand one hundred seventy-one feet at Cloud Peak, the highest summit in the range. The mountain stands inside a wilderness area of the same name, within the Bighorn National Forest, covering roughly one hundred eighty-nine thousand acres.

What makes Cloud Peak unusual among Wyoming summits is what happened, and did not happen, during the last ice age. The Bighorn Mountains were high enough and cold enough to accumulate glaciers during the Pleistocene, but the glaciers here were valley glaciers rather than the continental ice sheet that covered much of the Great Plains to the north and east. The mountain summit and portions of the high plateau above tree line retain soil and surface features that have never been scraped off by continental glaciation. Biologists working this terrain have documented plant communities and invertebrate populations that have existed continuously in this location for many thousands of years, isolated by altitude and geography from the lowland systems that the continental ice sheet reset.

The trail system in the wilderness accesses over thirty alpine lakes, most formed in cirques left by those Pleistocene valley glaciers. The lakes are cold, clear, and largely fishless in their natural state, though many were stocked with trout in the twentieth century by Wyoming Game and Fish.

Cloud Peak was first climbed in the recorded historical era in eighteen ninety seven, decades after government surveys of the region, including those involving geologist Ferdinand Hayden, had contributed to the campaign for Yellowstone's designation as a national park.