Geologic History Of The San Diego Region
200 million years ago San Diego was a seafloor, later gradually filled in by granitic rocks capped by volcanoes. 5 million years ago, the San Andreas fault system arose. Later Baja California pulled away from Mexico creating the Gulf of California. Several million years ago a branch of the San Andreas, our Rose Canyon fault, became active and pulled Point Loma away to form San Diego harbor. Monte Marshall, a fourth generation San Diegan with a Stanford PhD in Geology, worked for the US Geological Survey, began teaching and researching in SDSU Dept. of Geological Sciences.