Big Sur Quadrangle
Major physiographic features and tectonic blocks of the Point Sur 30 x 60 quadrangle
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USGS:
The Cambria 30´ x 60´ quadrangle comprises southwestern Monterey County and northwestern San Luis Obispo County. The land area includes rugged mountains of the Santa Lucia Range extending from the northwest to the southeast part of the map; the southern part of the Big Sur coast in the northwest; broad marine terraces along the southwest coast; and broadvalleys, rolling hills, and modest mountains in the northeast.
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This report contains geologic, gravity anomaly, and aeromagnetic anomaly maps of the eastern three-fourths of the 1:100,000-scale Cambria quadrangle and the associated geologic and geophysical databases (ArcMap databases), as well as complete descriptions of the geologic map units and the structural relations in the mapped area. A cross section is based on both the geologic map and potential-field geophysical data.
JOHN G. PARRISH, Ph.D., STATE GEOLOGIST [Source]:
The Point Sur 30’ x 60’ quadrangle covers approximately 5,000 km2 of northern Monterey and southwestern San Benito Counties, California. The area of this map extends about 80 km east-west from the coast at Point Sur to the Bitterwater Valley along the San Andreas Fault zone. It extends about 55 km north-south from Carmel Highlands to Lucia along the coast and from Soledad to San Ardo in the Salinas Valley. The Point Sur 30’x60’ includes much of the rugged Big Sur coastline, National Forest and wilderness in the Santa Lucia Mountains, and some of the richest farmland in the world in the Salinas Valley. The relief in the quadrangle ranges from about a thousand meters below sea level in submarine canyons to more than 1700 meters above sea level at Junipero Serra Peak in the Santa Lucia Mountains.
Residents and visitors are subject to potential hazards from earthquakes, debris flows and other landslides, floods, wildfires, and subsidence from ground water and petroleum withdrawal. Coastal areas are exposed to erosion by storm and tsunami waves and landsliding. This geologic map is intended to illustrate the distribution of the rocks and surficial deposits of the area and their structural and stratigraphic relations to one another. It provides a regional geologic framework as an aid to better evaluations of the potential for
hazard from active earth processes.
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The Point Sur 30’x 60’ Quadrangle lies entirely within the California Coast Ranges physiographic province and is underlain by four fundamentally different basement terranes of Mesozoic age: the Franciscan Complex, the Great Valley complex, the Schist of Sierra de Salinas, and the Salinian complex. The Salinian complex and the Schist of the Sierra de Salinas comprise the basement of the Salinian block, named for the city of Salinas, a northward-transported tectonic block bounded by the San Andreas Fault to the east and the Sur/Nacimiento Faults to the west. The basement of the Diablo Range block, east of the San Andreas and of the Nacimiento block west of the Sur/Nacimiento Faults are composed of Franciscan Complex and Great Valley Complex. The Salinian block is totally devoid of Franciscan and related rocks, whereas the Diablo and Nacimiento blocks lack granitic intrusive rocks. All of the basement blocks are covered in part by Cretaceous and Cenozoic sedimentary rocks, the distribution of which reflect varying amounts of movement on faults of the San Andreas system. Tectonic activity associated with the faults bounding these structural blocks formed the Santa Lucia Range, Sierra de Salinas, Gabilan Range, and the Diablo Range.