EEI > Issues & Policy > Environment > Environmental Excellence
Land: SCE
Southern California Edison Discloses Major Fossil Find at Substation

The most comprehensive collection of fossils of its era in Southern California, more than 1 million years older than those at the well-known La Brea Tar Pits, was discovered by Southern California Edison (SCE) paleontologists.

The historic finding occurred at a site in Riverside County on county-owned land where SCE is building its new El Casco Substation. As part of its work to prepare the land for the substation near San Timoteo Canyon, SCE had staff and contract paleontologists and biologists carefully monitor construction grading at the 28-acre site. Because of the soft sediments in the soil, SCE expected to find some fossils, but nothing close to the size and scope that was discovered.

The fossil collection contains specimens estimated to date back 1.4 million years to a period known as the Irvingtonian North American Land Mammal Age. The collection is about 1.2 million years older than those from the better known Late Pleistocene era, such as fossils at the La Brea Tar Pits.

The El Casco collection is estimated to contain more than 1,450 specimens, including about 250 large vertebrate fossils (bigger than rabbits) and about 1,220 smaller vertebrate fossils (rabbit size and smaller). More than 27 different kinds of fossils have been identified.

Some of the fossils discovered during construction grading last fall are extremely rare. Some are notable for their relative completeness. Among those are a small, saber-toothed cat known as Smilodon Gracilis, which is 1 million years older than its descendant a larger saber-toothed cat, Smilodon Fatalis, at the La Brea Tar Pits.

Currently, sediment is being removed from the fossils at a lab of LSA Associates, Inc. in Riverside, an SCE contractor. LSA also is cataloguing the fossils and reassembling and reconstructing some of the larger fossils and sorting microfossils.

For more information, please visit