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Subsection M261Ag
Upper Salmon Mountains

This subsection is near the center of the Western Paleozoic and Triassic Belt.  It includes the Marble Mountains and mountains from there south-southeast to Deadman Peak in the Salmon Mountains.  The climate is cold and humid.  MLRAs 5c and 5d.

Lithology and Stratigraphy.  This subsection is dominated by Mesozoic granitic rocks and Paleozoic to Jurassic metavolcanic and metasedimentary rocks, including serpentinized peridotite, of mostly Western Hayfork terrane, Rattlesnake Creek terrane north of the Marble Mountain fault, and Sawyers bar terrane south of the Marble Mountain fault.  Stuart Fork Formation terrane occurs in the south end of the subsection, southeast of the Soap Creek  Ridge fault.  The granitic rocks are generally quartz diorite to slightly more silicic rocks.  Quaternary glacial till and outwash occur in many small areas.

Geomorphology.  This is a subsection of mountains with rounded summits, steep sides, and narrow canyons.  The mountains are generally aligned toward the north, although the Marble Mountain fault strikes east-west.  There are many cirques and moraines in mountain valleys.  The elevation range is from about 4500 feet up to 8299 feet on Boulder Peak.  Mass wasting and fluvial erosion are the main geomorphic processes.  Glacial processes have also been prominent.

Soils.  The soils are mostly Lithic, Typic, and Pachic Xerumbrepts and Dystric Xerochrepts on metamorphic rocks, with Haploxerolls on marble.   Soils on granitic rocks are mostly Lithic, Entic, Typic, and Pachic Xerumbrepts.  Rock outcrop is extensive and Cryumbrepts, Cryochrepts, and Cryoborolls occur at higher elevations.  Typic Xerumbrepts occur on glacial till.  The soils are well drained, except in small glacial basins.   Soil temperature regimes are predominantly frigid, with cryic at higher elevations.  Soil moisture regimes are xeric.

Vegetation.   The predominant natural plant community is White fir series, with Red fir series, Mountain hemlock series, Mixed subalpine forest series, and Subalpine meadow habitats at higher elevations.

Climate.   The mean annual precipitation is about 60 to 90 inches.  Much of the precipitation is snow, especially at higher elevations.  Mean annual temperature is about 35° to 46° F.  The mean freeze-free period is about 25 days at higher elevations to 100 days at lower elevations.

Surface Water.  Runoff is rapid.  It drains to the Salmon, Scott, and Klamath Rivers and their tributaries.  Streams are mostly perennial.  There are many  small lakes, or ponds, in cirque and paternoster basins.

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