Early Excavations

black and white image of early la brea tar pits excavation

The asphalt seeps of Rancho La Brea have been of interest to humans since prehistoric times. 

Native Americans used the asphalt as a glue or caulk, and early Angelenos used it as a roofing material. Though the first recorded mention of the asphalt dates back to the 1769 Portola Expedition, it wasn't until 1875 that the animal remains found in the seeps were recognized as fossils by Professor William Denton. Later in 1908 they were made famous in an article written by J. C. Merriam called "Death Trap of the Ages."

Soon thereafter, more and more paleontologists, amateurs and professionals alike, became interested in the asphaltic fossils.  Los Angeles High School biology teacher James Z. Gilbert began a large excavation project in 1909, under the banner of the Southern California Academy of Sciences. Rancho La Brea's long history of encouraging volunteerism in the young started with Gilbert; his excavation team largely consisted of his own students from Los Angeles High School. His finds laid the groundwork for the founding of the Los Angeles County Museum of History, Science, and Art, which is today the Natural History Museum of Los Angeles County. Gilbert's Academy collections were some of the first specimens in the new museum in 1911, and mounted skeletons from Rancho La Brea were among the first displays in the museum when it opened in 1913.

The Hancock family purchased Rancho La Brea in the 1870s and encouraged the scientific investigation of the fossil deposits. While the Hancock family mined the asphalt and later industriously drilled for oil, a few small scale excavations were made between 1901 and 1910. From 1912-1913 a larger scale excavation was conducted by the University of California at Berkeley. In 1913, the Los Angeles County Museum of History, Science, and Art (which later became the Natural History Museum of Los Angeles County) launched a two year excavation project that recovered  a million fossil bones from 96 quarries or "pits."  The remains of several of these excavations are still on view to the public, including Pits 3, 4, 9, 13, 61/67, and of course, Pit 91.

Pit 4 historic excavation at the Tar Pits
Historic excavation at the Tar Pits shows Pit 4 after flooding in 1914

Led by L. E. Wyman, museum excavators earned $3.50 a day—decent wages for 1913—but worked in terribly dangerous conditions. Shoring methods were primitive, and floods and cave-ins were common. In addition, the newly recovered bones were scrubbed clean of asphalt with heated kerosene that caught fire from time to time. After this massive excavation and preparation effort, much of the ensuing scientific research on the newly discovered fossils was undertaken by Chester Stock. A graduate of the University of California, Berkeley, and a professor at the California Institute of Technology, Stock became one of the more famous North American paleontologists in large part for his research, discoveries, and publications on the fossils of Rancho La Brea.

Excavation at Rancho La Brea has continued, off and on, since the beginning of the twentieth century.

Although much of the surrounding landscape has changed immensely, many of our fundamental excavation techniques have remained the same: bones are excavated using small hand tools and field data is recorded with pen and paper.  Even our measurement system has its roots in the grid system laid out by excavators in 1913. We supplement and support these techniques with new technology—digital cameras document day-to-day progress quickly and cheaply, and computerized databases allow us to search through collections with a modicum of ease—but we doubt if anything will ever replace hand tools, pen, paper, and elbow grease. You can learn more about and visit our active excavation site today!