The George C Page Museum of La Brea Discoveries and “Project 23”

Deborah Painter (USA)

Los Angeles, California features among its many long boulevards a street that trends north to south for 34km: La Brea Avenue. This boulevard is named for a tranquil park a few city blocks from it, on Wilshire Boulevard. The park boasts animal statuary and the Pleistocene Garden, a recreation of the native vegetation that grew here during the Pleistocene epoch of the Quaternary period. This park also has a museum containing thousands upon thousands of animal and plant fossils preserved over a period of tens of thousands of years. This is the George C Page Museum of La Brea Discoveries at Hancock Park, 5801 Wilshire Boulevard on the site of the old “Rancho La Brea”, known more popularly as the La Brea Tar Pits (Fig. 1). The flora and fauna thus preserved represent a time from 50,000 BP (Before Present) to 10,000 BP.

“Brea” is Spanish for “tar”. Asphalt or petroleum seeps are crude oil deposits that are released at the earth’s surface. The volatiles dissipate, leaving asphalt (Fig. 2). Another interesting site not far away from the La Brea Tar Pits, readily accessible to visitors, is Carpinteria State Beach at 5361 6th Street, Carpinteria, California, near Santa Barbara, and the adjacent Tar Pits Park. Both are 135km northwest of the George C Page Museum.

The asphalt seeps directly onto the sand dunes at Carpinteria and is also visible in the near shore area. Many petroleum seeps are released on the ocean floor. Elsewhere in the world, several other land-based asphalt seeps have yielded Pleistocene megafauna fossils, such as the glyptodonts (giant armadillo like animals) excavated at Trinidad’s La Brea Pitch Lake. The name comes from the fact that, historically, sources of asphalt at the surface have been useful as “pitch” for boatbuilding or paving material in the Middle East and elsewhere.

The Los Angeles Basin’s most important geological features are its thick deposits of petroleum-rich silt, sand and clay, with many deep faults within, with these faults being part of the ongoing plate tectonics process in the region (which includes the famous San Andreas Fault). Crude oil seeps up along the 6th Street Fault from the Salt Lake Oilfield, underlying the portion of the Basin where Rancho La Brea is located, and has resulted in the large seeps one sees on Wilshire Boulevard.

The asphalt seeps are active and so a fence has been erected around them (Fig. 3). Wet, fresh material continues to bubble up from cracks in the sidewalks and streets just outside the Museum property, as the author herself noted on a visit to the famous Tar Pits. Prior to asphalt mining, this was a shallow seep covered in water, and not a pit.

A glimpse at the Basin thirteen thousand years ago forces us to reimagine the sprawling urban area as it was then. Pines, grasses and some of the familiar low brush species of the chaparral vegetative community dominate the landscape. The familiar Santa Monica Mountains form a backdrop.

Some of the Southern California animals would be readily identifiable, such as California scrub jays and coyotes, while others would be very different, such as:

• The dire wolves (Aenocyon dirus).
• Ancient bison (Bison antiquus, the direct ancestor to the modern American bison).
• Long horned bison (Bison latifrons), with two metre horns.
• Giant vultures (Teratornis; Fig. 4).
• Sabre-toothed cats (Smilodon; Fig. 5).
• American lions (Panthera; Fig. 5).
• Llamas (Hemiachenia).
• Western horses (Equus).
• Imperial mammoths (Mammuthus; Fig. 6).
• American mastodons (Mammut).
• Jefferson’s ground sloths (Megalonyx jeffersonii).
• Camels (Camelops), which appear at first glance like the Old World dromedaries, but taller and with longer necks.

Thirteen thousand years ago, the Basin’s climate was somewhat cooler and more humid than its modern Mediterranean type climate. Some humans lived here. Hunters and gatherers had made their way from Asia, by way of what we call Alaska, but so long ago that no memory of the journey was preserved in their culture.

The northern portion of the Basin featured a small, shallow lake, little more than a watering hole, partially covered with leaves and dust. The lake had an odd, pungent odour. Bubbles often rose to the surface, but the water was cool. Here, turtles, freshwater clams and small fish managed a precarious existence. That was because of the deadly, dark horror that lay hidden beneath the water: asphaltum, a solid bitumen that consists of dried, hardened asphalt, which provided a solid surface animals could walk upon, but only for a short distance. The water lured animals to drink, but instead delivered death to any too heavy to remain buoyant once they walked out past the hard and dried asphaltum and into the wet asphalt.

During any given week, at least one unfortunate animal lay along the shore. It might not have been megafauna, but instead a tiny victim, such as a beetle or small bird. No one, not even the few humans who wandered by could, if they wished, help any but the smaller animals, because that black, viscous horror was holding them fast.

Horses, mammoths and mastodons became mired, but the numbers of their victims are more sparsely represented than many other species, possibly in part due to their higher intelligence and ability to teach others of their herds to avoid this watering hole. Sabre-toothed cats, American lions and dire wolves sometimes joined vultures in seeking an easy meal and became trapped in what was clearly also a classic ‘predator trap’. However, the vultures could escape the fate of these large predators, if they could fly away before any part of their legs or wings touched the asphalt.

Such was the tragic legacy of this lake. New asphalt continued to rise to the surface. As the centuries passed, the lake continued to attract animals, but the animals no longer included the megafauna of the past. These were buried deeper in the lake, in hardened portions of asphaltum. And the humans grew in number and called themselves the Tongva and Chumash. They came to the lake occasionally and carefully scooped up small portions of the black, death-dealing horror, carrying it away in pots to waterproof their boats.

People from another continent moved here and made note of the lake, thinking it a geyser because of the bubbles of methane gas that rose up (Fig. 7). They chose to avoid it. The methane gas was the result of not only natural fractionation of the petroleum, but also the metabolic processes of over 250 species of bacteria consuming the asphaltum and releasing this gas.

As time went on, these new people, who called themselves the Spanish, realised they could also use the asphaltum. The old Mexican land grant known as Rancho La Brea was divided up into commercial and residential properties and later, Turnbull, Stewart and Company established a mine here in the year 1886 on property owned by George Allan Hancock. The miners dug deeper into the black material. In doing so, they made pits and found the skeletons of amazing animals forgotten by the earlier humans.

The mining company was eager to allow scientists to excavate the fossils because there were so many that they interfered with mining. Most of these fossils were in a remarkable state of preservation due to the asphaltum that shielded the organic matter in the bone marrow from bacterial action. A local high school teacher worked to arrange for funding for university excavations. Beginning in 1913, University of California palaeontologist John Merriam made many of the discoveries and had several species named for him.

The fossils went to the Natural History Museum of Los Angeles County under an exclusive agreement with the landowner. By 1940, the world had learned of these animals in newspaper and magazine accounts and, for decades, Hancock Park provided a place for visitors to enjoy the outdoors and walk their dogs. However, the tar pits remained fenced off to prevent mishaps. Fibreglass statues of ground sloths and mammoths reminded them of the rich diversity of life of the Pleistocene that was preserved here. The George C Page Museum of La Brea Discoveries, part of the Natural History Museums of Los Angeles County, was opened to the public in 1977. Named for a local philanthropist, it has an interesting architectural design, having many halls below ground surface, to give the impression of being in the excavations and surrounded by wetland plantings.

In 2006, the Los Angeles County Museum of Art at 5905 Wilshire Boulevard, adjacent to the George C Page Museum, began construction on a new parking garage. Sixteen new fossil deposits were discovered, including one with an almost complete skeleton of an adult Columbian mammoth. The challenge was to save the fossils while staying clear of the construction, which would require many months. The Museum’s first step was building large wooden boxes around the deposits. Twenty-three boxes loaded with asphaltum and fossils were moved to their present location at the La Brea Tar Pits for careful excavation and cleaning. Thus “Project 23” was born (Fig. 8). Box 14, as just one example, initially weighed 38,590kg.

In addition to the large boxes, Museum staff moved 327 buckets of fossil material from the art museum’s future parking garage site. Project 23 continues in 2021 and will doubtless keep the scientists engaged for a long time. The material in the boxes and buckets includes many typical La Brea fossils:

• A fossil bison.
• Turtles.
• Snails.
• Beetle parts.
• Leaves.
• Freshwater clams.
• Pollen and other microfossils.

Not surprisingly, these are helping science understand Los Angeles’ Ice Age ecosystem (Fig. 9). This site represents the older deposits, dating from 35 to 45 thousand years BP according to radiocarbon analysis.

The Museum has a program for teenaged volunteers and is open daily except Tuesdays. Admission per person is $15. For more information telephone (213) 763-3499 or contact the George C Page Museum by email at: info@tarpits.org.

One tusk of the mammoth, a bull nicknamed “Zed”, can be seen in the Museum. Both Columbian mammoths and Imperial mammoths have been found at Rancho La Brea. Columbian mammoths (Mammuthus columbi) of North America, and Central and South America, and Imperial mammoths (M. imperator) of the American Southwest were among the largest mammoths, larger and taller by far than the more celebrated woolly mammoths (M. primigenius). The range of the latter did not include the California area and the Columbian mammoth went extinct in Texas as recently as 7,800 BP.

A visit to the George C Page Museum of La Brea Discoveries includes a chance to see the scientists in their Fossil Lab through an enormous glass window, sorting, cleaning and labelling fossils. On select days, visitors can see volunteers excavating at Project 23 (Figs. 10 and 11). The author has thus far not visited any other natural history museum like this one, where visitors can observe the process onsite where the fossils occur. One can also talk with Gallery Interpreters about the life of Los Angeles long ago.

About the author

Deborah Painter is an ecologist and general environmental scientist specialising in transportation and industrial development planning to minimise deleterious environmental impacts. She lives in the United States.

References

CBS Los Angeles June 8, 2019 “Tar Continues to Ooze Up on Streets Near La Brea Tar Pits”: https://www.youtube.com/watch?v=3AoygZa3d_s

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