The Alpine Lakes Wilderness features some of the most rugged topography in the
Cascade Range with craggy peaks and ridges, deep
glacial valleys, and
granite walls spotted with over 700 mountain lakes. Geological events occurring many years ago created the diverse topography and drastic elevation changes over the Cascade Range leading to the various climate differences. Snowgrass Mountain is composed of
schist, part of the Nason
terrane laid down 210 million years ago. During the
Pleistocene period dating back over two million years ago, glaciation advancing and retreating repeatedly scoured the landscape leaving deposits of rock debris. The last glacial retreat in the Alpine Lakes area began about 14,000 years ago and was north of the Canada–US border by 10,000 years ago. The U-shaped cross section of the river valleys is a result of that recent glaciation.
Uplift and
faulting in combination with glaciation have been the dominant processes which have created the tall peaks and deep valleys of the Alpine Lakes Wilderness area. ==See also==