Repetitive multispectral ERTS-l (Earth Resources Technical Satellite-1) imagery of northern California has disclosed several systems of linear features that may be important for the interpretation of the structural history of California. Four linear systems coexist within the northern Coast Ranges. They are separated from an orthogonal system of linear features in the Klamath Mountains by a set of discontinuous east-southeast–trending linear features (the Mendocino system) which are traceable from the Pacific Coast at Cape Mendocino into the eastern foothills of the Sierra Nevada. Within the Sierra Nevada, the Mendocino system separates the north-trending Sierran system from a set characteristic of the Modoc Plateau.
With minor exception, little overlap exists among the systems, which suggests a decipherable chronology and evolutionary history for the region. The San Andreas system of linear features appears to truncate or coexist with most other systems in the northern Coast Ranges. The Mendocino system truncates the Klamath, Sierran, and Modoc systems. The Sierran system may represent fundamental and long-persisting early to mid-Mesozoic zones of crustal weakness which may have been reactivated during late Mesozoic time. The Mendocino system was possibly developed during mid- to late Mesozoic time, and recurrent movement has persisted into the Holocene Epoch. The Mendocino system is thus an important element in the structural framework of northern California.