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The Prehistoric Past of the Irvine Ranch Natural Landmarks

PictureFossilized marine life found in Fremont Canyon

The Irvine Ranch Natural Landmarks are full of rich geological features that act like a historical record of events over time, chronicling earth’s history dating back nearly 80 million years. Throughout that time, our local wildlands have been home to a wide range of plants and animals, including dinosaurs!
Many rare and unique features have been discovered by geologists who studied the Landmarks including fossils of hadrosaurian, or “duck-billed” dinosaurs. These findings were taken into consideration when the Irvine Ranch was being evaluated as a Natural Landmark designation. The Landmarks consist of a wide variety of rock types and diverse fossils exposed on the land, capturing the changing landscapes and evolutionary events over millions of years.

The terrain of the Landmarks ranges from picturesque coastlines subject to modern erosion and other natural processes, to rugged, uplifted mountains where the geologic history of Southern California is exposed from the late Cretaceous period (65 million to 80 million years ago) to the late Pleistocene period (less than one million years ago) and largely intact.
Learn more about our nation’s prehistoric past during National Fossil Day on October 13. National Fossil Day is celebrated every October on the Wednesday of Earth Science Week and is an annual celebration held to highlight the scientific and educational value of paleontology and the importance of preserving fossils for future generations.
Hosted by the National Park Service (NPS) and the American Geosciences Institute, this year will mark the 12th annual National Fossil Day, with a special focus on dinosaur related fossils. Join paleontologists, educators, and students in fossil-related events and activities across the country in parks, classrooms, and online during National Fossil Day by visiting
For more information about the Irvine Ranch Natural Landmarks and the rare species and geological features found on these native wildlands, visit