Finding Fossils in Lake Forest

While we’re still in January—the month of beginnings—I've decided to put El Toro’s pioneer story on hold, focus on another type of beginning, and travel even a bit further back in time.

How much further? Well, how about to when this area was underwater?

And no, I’m not talking economics. I’m talking about a time, millions of years ago, when what we call the Saddleback Valley was completely immersed by what is now known as the Pacific Ocean.

Instead of beginning at that beginning, however, let's first meet Lake Forest resident and Heritage Hill volunteer Jim Krause.

The Perfect Storms

The first thing you should know about Jim is that he and his family have lived in Lake Forest for more than 35 years. The second and third? That he enjoys taking walks, and that he has long enjoyed the study of prehistoric life, otherwise known as paleontology.

In the spring of 1998 these three elements all came together. Orange County had just emerged from a series of El Niño storms that began the first week of December 1997—when some areas of the Saddleback Valley were pelted with as much as 10 inches of rain per day—and continued, off and on, into the following March.  

Jim has written a fine essay on the subject, so at this point I’ll let him pick up the story.

I have resided in Lake Forest since 1976. I walked Serrano Creek with a series of dogs for over twenty years without noticing any fossils. This changed when El Niño hit and ravaged the creek with a storm that dropped about eight inches of rain in one day. 

Shortly thereafter I began to find petrified whale bones and bones and teeth of other animals in the creek bottom. Because the creek is on County property, I contacted the County and advised them of my discoveries. The County sent a representative along with several paleontologists to review my finds. They identified many of the fossils and took some of the more interesting specimens for the County’s archives.

Included in the finds were parts of whale, sea lion, shark, dolphin, and various shell fish. These are marine fossils from the Miocene Epoch when all of Orange County was underwater, about twenty three million to five million years ago. Mixed in with the marine fossils were fossils of terrestrial mammals. These terrestrial fossils were from the Pleistocene (Ice Age) Epochs when Orange County was being uplifted and rising from the seas. 

The Pliocene and Pleistocene together lasted from about five million to ten thousand years ago. The terrestrial fossils included parts of mammoth and gomphothere that are extinct members of the elephant family. I also found parts of an extinct bison and Ice Age horse. Two finds that were impossible to date were a chunk of petrified wood and piece of an ancient palm tree. 

Mixed in with the fossils were Indian artifacts. These included metates, manos (a hand-held stone or roller for grinding corn or other grains on a metate), mortars, pestles and numerous small tools. One mortar was of special interest.  It had been made from an extremely hard rock called basalt and was so perfectly formed that it appeared to have been turned on a lathe. The mortar had been broken and then repaired with asphaltum, a naturally occurring tar such as found in the La Brea Tar Pits. 

I also found a shard of incised pottery that is very rare and probably traded from elsewhere since the local peoples did not have a history of making pottery. Some brilliant blue nodules found scattered in twisted and folded silt beds are currently under analysis to determine what they are. Overall, this is an extremely rich and varied assortment to be found in a mile and a half stretch of creek bed.

Fossil Futures

When the creek washed the fossils and artifacts from their original locations and indiscriminately mixed them in the streambed with other materials, they lost their identification to their source or, as it is called, their “provenance.” This loss of provenance means that while the fossils and artifacts may have interest to the amateur, their value to scientists and museums is considerably diminished. 

My interest in these fossils and artifacts is not to build a collection. The enjoyment is in finding, studying, preserving, and sharing them. I have turned most of the artifacts over to an archeologist member of the local Acjachemem Nation. If the fossils and artifacts had remained in the creek, they would have soon been destroyed by erosion and foot traffic. When they, along with any other debris, reach the concrete channel at Bake Parkway, they are summarily removed and disposed of in a landfill.

There were plans to line Serrano Creek with concrete to prevent further erosion and to protect creek side properties from damage. A group of dedicated local residents who wanted to keep the creek natural, joined together and formed the Serrano Creek Conservancy. Through their extraordinary efforts, the plan for the concrete channel was abandoned and with Federal, County, City and private organizations joining with the Conservancy, the creek was stabilized by earth fill, realignment, and placement of rock structures.  The newly created banks were planted with erosion preventing native shrubs and trees to stabilize the banks and to provide habitat for birds and animals. This control of erosion has considerably reduced any uncovering and depositing of additional fossils.

Advice For Would-Be Paleontologists

Anyone considering searching for fossils in Serrano Creek should keep several things in mind. The creek is on County property and anything found that is of significance should be cleared with a representative of the County. 

The best method in amateur fossil hunting is to let the creek work for you and to walk the creek while checking the creek bottom and sides. Digging should not even be considered since there is no indication as to where to dig and you would have to move tons of earth to find anything since most of the soil is devoid of fossils. The creek banks are often steep and unstable and any digging would be dangerous and would contribute to erosion and stabilization of the cliffs. 

Anyone looking for dinosaur fossils would be most assuredly disappointed. Only five dinosaur fossil bones have been found in all of Orange County. Dinosaurs are terrestrial animals and Orange County was under water during the age of the dinosaurs. The five bones found were washed in from an area east of the Santa Ana Mountains which did not exist at the time.

Buggy Barn Exhibit

As Jim has noted, not only are a number of his "finds" now residing within County archives, but many that were not claimed by the County he gave to a Native American archaeologist. 

Still, that left Jim with a respectable number of artifacts, currently on exhibit at Heritage Hill Historical Park. The items are on display in a small structure which Hill employees refer to as the Buggy Barn since it houses a turn-of-the-nineteenth-century vehicle wonderfully restored by longtime volunteer Leroy Evans.

We’ll be talking more about Leroy and his many wonderful contributions to the Hill in another El Toro & Before. But for now, back to that exhibit and a few comments from Jim:  

Most of the fossils in the exhibit are marine fossils from the Miocene Epoch.  During this period, Orange County was marine habitat. The life forms in the exhibit from this time are parts of whale, dolphin, shark, oysters, abalone, clams, fish and sand dollars.

Although many of the marine animals are very similar to those now present in our coastal waters, others are now extinct, such as the megaladon shark which was much larger than a great white.

The only shark fossils in the exhibit are teeth. There's a reason for this. A shark does not have bones—it has cartilage. Cartilage does not preserve or petrify like bone. 

So as Jim has said, you'll find no dinosaur or shark skeletons on display at Heritage Hill's Buggy Barn. But what you will see is a fascinating array of fossil artifacts ... more than enough for anyone to "ooh" and "ah" about!