 During the last ice age small glaciers sculpted the Siskiyou basins that now contain lakes and meadows.At the lowest elevations of the Red Buttes Wilderness is found a magnificent old-growth forest of ponderosa pine, sugar pine, Douglas-fir and incense-cedar, with an understory of Pacific madrone, canyon live oak, and chinquapin.On the higher slopes are found white fir, Shasta red fir, and mountain hemlock.