This is a folded and sinuous northeast-dipping intra-Franciscan zone of thrusts that is delineated by a narrow belt of serpentinite dipping northeastward under the UCMA.

[7] Five thousand years ago there was a massive landslide on the southern slope of Cow Mountain that filled the channel from Clear Lake to the Russian River.

The more mesic northern exposures and ravines hold mixed chaparral and trees such as blue oak (Quercus douglasii), black oak (Quercus kelloggii), Douglas fir (Pseudotsuga menziesii), California nutmeg (Torreya californica) and California bay laurel (Umbellularia californica).

[13] Non-native invasive species include yellow starthistle (Centaurea solstitialis), medusahead (Taeniatherum caput-medusae), Italian thistle (Carduus pycnocephalus), bull thistle (Cirsium vulgare), arundo (Arundo donax), jubata grass (Cortaderia jubata), scotch broom (Cytisus scoparius) and Harding grass (Phalaris aquatica).

[13] Prescribed burning of the chaparral on south facing slopes has been used to improve the habitat for deer and other wildlife by giving them access to younger and more protein-rich vegetation.

[17] The headwaters of Scotts Creek on South Cow Mountain were severely burned in 2018 by the Mendocino Complex Fire, which may have increased erosion and the flow of sediments and dissolved nutrients into the Clear Lake.

[18] The 40 acres (16 ha) Lost Valley Meadow in South Cow Mountain is an Area of Critical Environmental Concern (ACEC) with a unique assemblage of native vegetation in the Miner's Ridge watershed of the Russian River Drainage system.

[19] Year round resident mammals include Columbian black-tail deer (Odocoileus hemionus), feral pig, western gray squirrel, brush rabbit, coyote, bobcat, cougar and raccoon.

[20] Special status species include Foothill yellow-legged frog (Rana boylii), Fisher (Martes pennati pacifica) and Western pond turtle (Emys marmorata).

[12] Migratory Birds of Conservation Concern are peregrine falcon (Falco peregrinus), prairie falcon (Falco mexicanus), burrowing owl (Athene cunicularia), long-billed curlew (Numenius americanus), rufous hummingbird (Selasphorus rufus), Lewis's woodpecker (Melanerpes lewis), olive-sided flycatcher (Contopus borealis) and Lawrence's goldfinch (Carduelis lawrencei).

[26] The North Cow Mountain Recreation Area covers about 26,000 acres (11,000 ha) of public land that is managed for non-motorized use.

[3] South Cow Mountain OHV Recreation Area covers about 23,000 acres (9,300 ha) of public land managed for off-highway vehicle use.

[28] Apart from erosion on the trails in South Cow Mountain, problems include vandalism, rowdiness at night, irresponsible shooters who damage signs and trees and litter the ground with shotgun shells, illegal dumping and tire burning.