Franciscan Assemblage

The Franciscan complex ( also Franciscan Formation, Franciscan Group, Franciscan Assemblage, Franciscan Series) is made ​​up of very different kinds of rocks, more than a thousand kilometers of rock unit on the west coast of North America from Oregon in the north to Southern California, the large parts of the San Francisco Peninsula builds. It is named Terrane geologist Andrew Cowper Lawson, of the San Andreas fault named that runs through the complex.

Rock content and tectonics

The Franciscan complex consists of very different types of rocks. Represented are mafic volcanic rocks ( "Green Stones" ), deep-sea cherts, gray wacken -like sandstones, limestones, serpentinites, slate and metamorphic rocks, all disturbed, zerschuppt and mixed on seemingly chaotic manner ( tectonic mélange ).

The complex is the main component of the California coastal mountains. The remarkable tectonic folding and scaling of the stacked layers are an image of the plate tectonic forces that created the coastal mountains of the American West. The association of the complex with the ophiolites of the Coast Range and the rocks of the Great Valley emerged as accretionary prism by the subduction of the Pacific, mainly oceanic crust beneath North America as well as the inclusion in the lateral displacement along the San Andreas Fault and the accompanying disorders.

Prehistoric tools from flint franciscanischem

According to archaeological finds of prehistoric Native American stone tools from flint franciscanischem in the western United States, that the material was traded over longer distances and so that already at that time there was a trading network between the various tribes. An example of this is appropriate findings in Central California, demonstrating a trade of the tribes in the San Francisco Bay Area with the Chumash.