Mt. Ellen-Blue Hills

The Blue Hills, in the northern and western portion of the WSA, are low mesas and barren badlands carved by erosion from blue-gray marine shales. The Mt. Ellen portion of the WSA consists of steep slopes and rounded peaks, including Mt. Ellen, with large basins and wide canyons. Mt. Ellen is part of the Henry Mountains, well-known in American geology for classical studies of intrusive mountain structures, upturned sedimentary rocks, and stream gradients. Mt. Ellen is the largest structural dome in the Henry Mountains, with a diameter of 12 to 15 miles. Predominant vegetation at the lower elevations is pinyon-juniper and saltbrush. Ponderosa pine, Douglas fir, and alpine fir grow at the higher elevations.