Subsection M261Aq
North Trinity Mountain

Lithology and Stratigraphy.  This subsection is dominated by Mesozoic granitic rocks and by Paleozoic to Jurassic gabbro and metavolcanic and metasedimentary rocks, including serpentinized peridotite, of the Western Hayfork and the Sawyers Bar terranes.  The granitic rocks are generally quartz diorite to slightly more silicic rocks.

Geomorphology.  This is a subsection of mountains with rounded ridges, steep sides, and narrow canyons.  There are a few cirques on the north sides of the higher mountains.  The elevation range is from about 4000 feet up to 7478 feet on Limestone Ridge.  Mass wasting and fluvial erosion are the main geomorphic processes.

Soils.  The soils are mostly Typic, Lithic, and Pachic Xerumbrepts.  Typic and Dystric Lithic Xerochrepts occur at lower elevations.  There are some Haploxeralfs, particularly  on highly serpentinized peridotite.  Rocky Lithic, Entic, and Typic Cryorthents occur at higher elevations. The soils are well drained.  Soil temperature regimes are mostly frigid, with some cryic at higher elevations.  Soil moisture regimes are xeric.

Vegetation.   The predominant natural plant communities are White fir series, and at higher elevations, Red fir series.   Jeffrey pine series occurs on serpentinized peridotite.  Mountain hemlock series, Mixed subalpine forest series, and Subalpine meadow habitats occur at higher elevations.

Characteristic series by lifeform include:
Grasslands: Montane meadow habitat, Subalpine meadow habitat.
Shrublands: Brewer oak series, Bush chinquapin series, Greenleaf manzanita series, Holodisus series, Huckleberry oak series, Montane wetland shrub habitat, Montane wetland shrub habitat, Mountain alder series, Sadler oak series, Sitka alder series, Subalpine upland shrub habitat. Subalpine wetland shrub habitat, Tobacco brush series, Wedgeleaf ceanothus series.
Forests and woodlands: Black oak  series, Douglas-fir series, Incense-cedar series, Jeffrey pine series, Mixed conifer series, Mountain hemlock series, Red fir series, Western white pine series, White fir series.

Surface Water.  Runoff is rapid.  It drains to the Trinity and Klamath Rivers and their tributaries.  Streams are mostly perennial.  There are some small lakes in the subsection.