page_title: San Diego–Tijuana
section_title: Geology
hierarchical_section_title: San Diego–Tijuana / Geology
caption_attribution_description: Español: cerro de las abejas Tijuana,México
context_page_description: San Diego–Tijuana is an international transborder agglomeration, straddling the border of the adjacent North American coastal cities of San Diego, California, United States and Tijuana, Baja California, Mexico. The 2012 population of the region was 4,922,723, making it the largest bi-national conurbation shared between the United States and Mexico, the third-largest shared between the US and another country, and the fourth-largest in the world. In its entirety, the region consists of San Diego County in the United States and the municipalities of Tijuana, Rosarito Beach, and Tecate in Mexico. It is the third most populous region in the California–Baja California region, smaller only than the metropolitan areas of Greater Los Angeles and the San Francisco Bay Area.
  The largest centers of the urban area maintain global city status and as a whole the metropolitan region is host to 13 consulates from Asian, European, North American, Oceanian, and South American nations. Over fifty million people cross the border each year between Tijuana and San Diego, giving the region the busiest land-border crossing in the world.
context_section_description: The land on which San Diego–Tijuana sits is due west of a major transform fault. The transform fault, known as the San Andreas Fault was created during the Cenozoic Era by the movements of the Pacific Plate and North American Plate. The region experiences earthquakes and felt the shocks of the 2009 Gulf of California earthquake and 2010 Baja California earthquake.
  The main mountain ranges of the Peninsular Ranges ridging eastern San Diego–Tijuana are the Palomar Mountains, Laguna Mountains, Sierra de Juárez, and the peaks of the Cuyumacas including Cuyamaca Peak. The highest points are located in the Lagunas at 6,378 feet (1,944 m) and in the Cuyumacas at 6,512 feet (1,985 m) while the highest is the peak of Hot Springs Mountain at 6,535 feet (1,992 m). These mountain ranges constitute part of the Salinian Block, a largely granitic terrane dating back to the Mesozoic era and thus explaining the abundance of such stone throughout the region. Once part of the North American Plate, the Salinian block broke off due to the formation of the San Andreas Fault and rift resulting in the Gulf of California and its extension of the Salton Trough.
  The faults nearest the urban area are the Elsinore and Laguna Salada faults, both secondary to the San Andreas fault.
caption: Cerro de Las Abejas.
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