Wildlife | Trees & Vegetation | Archaeology | Geology

The term "high sierra" relates to alpine areas above the main forest zone at 8000' elevation and above. The land is characterized by glacier- carved open peaks and basins. 100 million years ago vast amounts of molten granite were injected into and under the overlaying strata and crystallized into a huge mass of solid granite. The forces of erosion over time began to expose the granite. 60-70 million years ago, this granite mass was uplifted on the east side, creating a steep eastern and gentle westward slope. A series of volcanic flows covered portions of the central sierra. Beginning about 12 million years ago, the entire range was uplifted several thousand feet along the faults of the eastern flank. The increased grade accelerated the cutting action of westward flowing streams. As the crest of the sierra was thrust above snowline, glaciers formed, sculpting the high country, mostly during the last 1 million years. This area, received great supplies of moisture-laden air from the Pacific and a large ice cap formed. Only the highest peaks protruded from this mass. 1500-foot thick glaciers sculpted the sides of these mountains and canyons below as they slowly advanced.

Today most of the prominent peaks within the Byway corridor are remnant volcanic flows that stood above the glaciers. They have successfully resisted erosion for millions of years. The valleys below generally were scoured to the granite bedrock. This is apparent at Lake Alpine and many other locations where volcanic bluffs form the skyline with sculpted granite bedrock in the foreground. Evidence of the glaciers exist along the roadside near Big Meadow. Huge boulders were stripped from the highcountry and plowed to the side as the glacier advanced. These "erratics" litter both sides of the highway through this zone. They now rest more than 1000' above the river that was filled with icy debris to this level. The last glacier ended its advance creating a terminal moraine in the Arnold area about 13,000 years ago.