Published on December 22, 2022, Updated on December 23, 2022
Fossil Reef Park is the only preserved portion of Fossil Reef in Orange County and is 17 million years old. It is a tropical shell reef associated with beach sand rich in fossils. The park has 48 fossil marine vertebrate species, including shark teeth and Desmostylus.
In 1972, when Lake Forest was graded, A massive limestone formation was uncovered. Local paleontologists dubbed the location “Pecten Reef” due to the abundance of Pecten shells discovered there. These exposures depict the ocean floor 17 million years ago. The site was destroyed by a housing development after minimal research. In 1973, a second reef exposure was discovered in Laguna Hills. The Natural History Foundation of Orange County collaborated with the planning staff of the Orange County Environment Management Agency and the landowner of Affordable Communities to protect a portion of the reef. In 1982, the Orange County Historical Commission designated the exposed fossil ridge as a county prehistoric site and dedicated the 1-acre Fossil Reef Park in Laguna Hills.
The reef is unique because tectonic uplift and weathering processes have exposed an ancient portion of the sea floor. During the last million years, the uplift created the Santa Ana Mountains and the San Joaquin Hills. The brittle limestone did not yield during uplift but instead fractured along regional faults. A fault appears to extend in an east-west direction beneath the scoreboard on the high school baseball field and across the northwest corner of the park.
The marine muds that subsequently covered the limestone contained fossilized plankton, shark teeth, fish bones, marine mammal bones, and seaweed impressions.
Fossil Reef Park
25555 Alicia Pkwy, Laguna Hills, CA 92653, United States
Phone: +1 949-707-2680
Go southwest toward Community Center Dr
Turn left onto Community Center Dr
Turn left onto Alicia Pkwy
Drive to your destination – Laguna Dental Center 233 ft