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Take a virtual field trip of the geology of Laguna Beach to learn how sea caves, coves and tide pools relate to faults, dikes, and breccia - or try it out yourself! Here are the stops:
Stop 1: Three Arch Bay (private access or be a really good swimmer) – Check out the arches and sea caves on the north side and see if you can spot the faults
Stop 2: Thousand Steps – Take a look at the San Onofre Breccia up close
Stop 3: Table Rock – Perhaps the most picturesque erosional feature in Orange County
Stop 4: Treasure Island – Arr! There be tide pools and faults beneath the Montage
Stop 5: Victoria Beach – There’s some breccia and a few small faults, but mostly just pretty
Stop 6: Cress Street – The geologic boundary between North and South Laguna
Stop 7: Crescent Bay Beach – The southeastern point is breccia but the northwestern point is a andesitic dike. Pay close attention to the contact between the dike and the shale – the shale has been folded into a syncline from intrusion of the dike
Sources:
Atwater, Tanya. Tectonic History of Western North America and Southern California https://www.youtube.com/watch?v=nS_lMsBdafI&ab_channel=RapPar
Fritsche, A. E., Weigand, P. W., Colburn, I. P., and Harma, R. L., 2001, Transverse/Peninsular Ranges connections - evidence for the incredible Miocene rotation, in Dunne, G., and Cooper, J., compilers, Geologic excursions in southwestern California: SEPM (Society for Sedimentary Geology), Pacific Section, book 89, p. 101-146.
Morton, Douglas M., Fred K. Miller, Pamela M. Cossette, and Kelly R. Bovard. Geologic Map of the San Bernardino and Santa Ana 30ʹ X 60ʹ Quadrangles, California. US Geological Survey, 2006.
Stuart, Chalres J. "Lithofacies in the San Onofre Breccia, Laguna Beach to Dana Point, Orange County, California: a preliminary report." (1973): 55-58.
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