The map shows the three belts (Coastal, Central, and Eastern) that make up the Franciscan Complex. In general, the Coastal Belt is only weakly deformed, the Central Belt is chaotic, and the Eastern Belt is highly deformed. The metamorphic grade, i.e., the temperatures and pressures to which the rocks have been subjected, increases from the Coastal Belt to the Eastern Belt. The respective metamorphic facies are mainly zeolite, prehnite-pumpellyite (with blueschist blocks), and blueschist (with eclogite blocks). Metamorphic facies are described in the next figure.
Courtesy of the Open University, © Open University 2013