The underlying rock of the Puente Hills from the Bedford and Southern California Batholith basement to the Miocene and Pliocene sandstone, siltstones, and shale tells us a story about the natural history of the Puente Hills, about how they were made and how they came to be Hills. This was not a short process. Time passed slowly but […]
The third event recorded in the rock of the Puente Hills is the laying down of thick rock layers, which were subsequently uplifted. For over 10 million years in the marine basin opened by the rotation of the Transverse Ranges, the Los Angeles Basin and the nascent Puente Hills accumulated thick layers of sedimentary rock. The […]
The second event recorded in the rocks of the Puente Hills began some 23 million years ago. The trench system, which had for so long dominated the formation of Southern California, ended around 28 Ma, when the Pacific Plate transform convergence replaced the Farallon Plate trench system. As the “trailing edge of the Farallon Plate entered the […]