[2] Much of the mountain structures are pillow basalt formations created during the volcanic period and then uplifted with the collision into the North American Plate.

[2] Other geologic features are mainly the result of erosion and weather forces carving steam beds and valleys out of the rock formations.

[2] The Oregon Coast Range is home to over 50 mammals, 100 species of birds, and nearly 30 reptiles or amphibians that spent a significant portion of their life cycle in the mountains.

[6] Aquatic life includes river lamprey, Pacific lamprey, coastal cutthroat trout, Millicoma longnose dace, Umpqua chub, red-legged frogs, southern seep salamander, western pond turtles, coho salmon, Chinook salmon, steelhead trout, and others.

On the southern end the Coquille River's middle fork provides the general dividing line between the Central Range and the Klamath Mountains to the south and east.