Subsection M261Ah
Scott Valley

Lithology and Stratigraphy.  Scott Valley is filled with alluvium derived from Paleozoic to Jurassic metavolcanic, metasedimentary, plutonic, and ultramafic rocks of the Western Paleozoic and Triassic, Eastern Klamath, and Central Metamorphic Belts that are in the mountains around the valley.   Chaparral Hill is composed of Stuart Fork  Formation rocks and Quartz Hill is in Sawyers Bar terrane of the Western Paleozoic and Triassic Belt.

Geomorphology.  This subsection is dominated by a nearly level basin floor and by sloping alluvial fans that skirt the valley.   Slopes on the hills are mostly steep.  The elevation range is about 2700 on the valley floor up to 4238 feet on Quartz Hill.  Fluvial erosion and deposition are the main geomorphic processes.

Soils.  The soils are mostly Fluvaquentic Haploxerolls and Fluvaquentic Endoaquolls on basin floor and Xerochrepts and Argixerolls on alluvial fans.  Ultic Haploxeralfs occur on the hills.  The soils are well to poorly drained.  Soil temperature regimes are mesic.  Soil moisture regimes are xeric and aquic.

Vegetation.   The predominant natural plant communities are Oregon white oak series, Ponderosa pine series, and Native grassland, Sedge meadow, and Emergent aquatic communities.  Ponderosa pine series and Douglas-fir - ponderosa pine series occur around the margins of the valley and on hills in the valley.

Characteristic series by lifeform include:
Grasslands: Bluebunch wheatgrass series, California annual grassland series, Idaho fescue series, Sedge series, Tufted hairgrass series.
Shrublands: Birchleaf mountain-mahogany series, Wedgeleaf ceanothus series.
Forests and woodlands: Black oak series, Douglas-fir - ponderosa pine series, Oregon white oak series, Ponderosa pine series, Water birch series, Western juniper series.

Surface Water.  Runoff is moderately rapid from alluvial fans and slow from basin floor.  It drains to the Scott River, which flows through the subsection.  There are no natural lakes in the subsection.