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Ecological Types

Bolam/Andesite

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Click to see larger ecotype map of Mount Shasta This map area occupies the lower elevations on Mount Shasta's northern flank between 3500 and 5500 feet (1067 and 1676 meters) elevation. It is formed by MUDFLOW deposits, PYROCLASTIC flows, and DEBRIS AVALANCHES. This material originated higher on the mountain and came to rest on the gently sloping plain of this map area. These processes combined to form a complex landscape of deep, sandy, droughty soils, and cobbly outwash terraces.

Quicktime panorama of Mount Shasta from the North
Panorama of Mount Shasta from the North
©1999 G. Donald Bain, Virtual Guidebooks

This map area lies in Mount Shasta's "rain shadow." The sparse rainfall supports a desert-like vegetation type including western juniper, sagebrush, bitterbrush, mountain mahogany, and ponderosa pine.

Western juniper and curl-leaf mountain mahogany communities occupy Mount Shasta's lowest northern slopes. In Mount Shasta's rain shadow, the precipitation in this area is less than 15 inches per year.
Western juniper and curl-leaf mountain mahogany communities occupy Mount Shasta's lowest northern slopes. In Mount Shasta's rain shadow, the precipitation in this area is less than 15 inches per year.
Photograph by Peter Van Susteren

Stands of Ponderosa pine with a bitterbrush understory occupy much of Mount Shasta's northern slopes. This is one of the farthest west stands of "Eastside Pine" ecological type. This community is adapted to the droughty sites in Mount Shasta's "rain shadow". Yearly precipitation is about 20 inches.

Ponderosa pine with Mount Shasta in the distance
Ponderosa pine with Mount Shasta in the distance
Photograph by Peter Van Susteren

The most prominent feature is Whitney Creek. Whitney Creek is known to flood with climatically-triggered mudflows. The most recent occurred in 1997 when it covered Highway 97 with over 30,000 cubic yards (23,000 cubic meters) of mudflow debris.

Videoclip of August 1997 Whitney Debris Flow
Videoclip (MPEG) of Whitney Debris Flow, August 1997
Full video available for viewing at
U.S. Forest Service
McCloud Ranger Station
McCloud, California 96057
(530) 964-2184
 

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