|Colorado Desert District CALIFORNIA STATE PARKS®|
When most visitors
think of Anza-Borrego Desert State Park, located in southern
Colorado Desert, they usually envision wild flowers,
bighorn sheep, or
arid landscapes framed by rugged mountains. Few realize that the
badlands of Anza-Borrego provide a contrasting view, a window
into the region's vanished past. The Park was not always the arid
desert we experience today.
The key to understanding this prehistoric
paleontology, the study of the fossilized remains of
ancient life. And Anza-Borrego has an exceptional fossil record.
Over 500 different types of organisms have been identified, ranging
form microscopic plant pollen and spores to the largest of
Not only are the bones and teeth of long extinct animals preserved,
but in some places, also their tracks.
Salton Trough, a geologically active rift
valley, which bounds the eastern edge of the Park once held a
northward extension of the
Sea of Cortez. Sediments laid down 5
million years ago in these warm clear tropical waters, now yield the
preserved shells of a variety of
snails, crabs, and
These organisms have ties with the Caribbean Sea, and record a time
before the Isthmus of Panama had formed. The remains of fish,
walrus, baleen whales and even sea cows help us to more fully
picture this long extinct marine ecosystem.
About 4 million years ago, the ancestral
Colorado River began cutting through the
Colorado Plateau of Arizona
and Utah. The sediments eroded during the formation of the
Canyon spilled into the Salton Trough, creating a vast delta. These
brackish marine deposits are recognized in the Park today by their
shell reefs and
fossilized wood. The types of tress represented now live along
the Pacific coast of southern California suggesting that any
mountains west of the Trough must have been low.
As the Salton Trough was filled with sediment
carried by the ancestral Colorado River, what was to become Anza-Borrego
gradually changed from a predominately marine environment to a
system of interrelated terrestrial habitats. By about 3 million
years ago, most of the area once covered by the Sea of Cortez held a
large, inland lake. Here, the remains of fresh water clams, snails,
and fish are not uncommon. Streams and rivers draining the new
Peninsular Range mountains, which border the western side
of Anza-Borrego today, spread an apron of alluvium and floodplain
deposits eastward into the Salton Trough. It is these sediments that
provide us an almost uninterrupted record of terrestrial habitats
spanning a period form about 3 million to less than a half million
years ago. During this time, Anza-Borrego supported a rich diversity
of wild life. Herds of mammoth elephants, tapirs, zebra-like horses,
several species of camels, and llamas ranged across a landscape of
stream border woodlands and savannah-like grassy scrublands. And,
had we been there, we may have glimpsed a foraging giant ground
sloth, beaver, or even a saber-toothed cat or American cheetah on
Since the 1930s, paleontologists have documented the extensive terrestrial and marine fossil record preserved in the sediments deposited along the western Salton Trough and the Gulf of California. These deposits span approximately the last twenty million years. Over 500 different organisms have been identified, ranging from microscopic marine plants and shell fish to the largest of Mammoths. Not only are the bones and teeth of animals preserved, but in some places also their tracks.Anza Borrego Desert State Park is home to the world class Stout Research Center Paleontology Lab (pictured here) where fossilized remains of extinct animals like mammoths and saber toothed cats are prepared, documented and cared for to be used by scientists all over the world.
The Colorado Desert District and Anza-Borrego Desert State Park paleontology staff are responsible for protecting and managing these internationally significant paleontological and geological resources. An annual Paleontology Certification Training Program, which consists of classroom instruction, curation and laboratory training, and field exercises is conducted each year from November through May. This program was developed to provide and maintain professional credentials for paleontology volunteers.
The paleontology volunteer program at Anza-Borrego Desert State Park has been active for over 20 years and in October 1993 the Anza-Borrego Desert State Park Paleontology Society was formed under the direction of George Miller, paleontologist.. This volunteer group assists the District and State Park staff conserve and manage the Park's vast paleontological resources and collection. Those interested in participating in the program may visit their website at: www.anzaborregopaleo.org or call or write for further information at:
T. Jefferson, District Staff
Desert District Stout Research
Anza-Borrego Desert State Park
Springs, California 92004
Downs, T., and J.A. White, 1968.