Formation[ edit ] Illustration of several species getting mired in the tar pits Tar pits are composed of heavy oil fractions called gilsonitewhich seeped from the Earth as oil. The tar pits visible today are actually from human excavation.
Indians, Tar Pits and Tar Mines Spanish explorers traveling through California in the late s observed Yokuts Indians using asphalt for many purposes. In particular, the Tulumne Yokuts collected tar from natural seeps that oozed up near their village of Wogitu, near McKittrick on the west side of the valley.
The asphalt was molded into fist-sized tar balls for trading, waterproofing, and as an adhesive. It was also used for decorating by inlaying bits of abalone shell into tar stuck on pottery, knives, masks, and clothes.
When Pahmita Dumna Yokuts, was about years old, he remembered watching pioneers at Oil City, near Coalinga, collecting tar from the same seeps he and his family once mined. Seeps were also being worked about this time at McKittrick and Taft, west of Bakersfield, sites where Yokuts once collected tar as well.
The pioneers used the tar they collected mainly for waterproofing roofs and greasing wagon wheels. Inevitably, the Wogitu tar seeps attracted the attention of entrepreneurs who sought to capitalize on this unusual resource. The most successful entrepreneurs were John Hambleton and Judge Lovejoy who in dug shallow pits8 to 10 feet deep, near active seeps in what became known as the Asphalto area.
They built a small still and refined the tar they collected into lamp kerosene which was shipped by wagon to their agents in Stockton.
Working the asphalt pits was difficult and dangerous. Valley temperatures often hovered around degrees, reaching as high as degrees in the pits.
Consequently, work was limited to twenty-minute shifts, lest the workers become debilitated by the heat or overcome by noxious fumes rising from the seeps.
Byseveral 5-foot by 6-foot foot shaftsmany lined with railroad ties for stability, were sunk up to one-hundred feet deep into the McKittrick tar seeps. Because the miners working these shafts quickly became covered with asphalt, they usually worked naked.
At days end, they cleaned themselves with case knives or wooden scrapers made for race horses, then washed with distillate.
Rather than dig pits, some prospectors, many of them former Mother Lode miners, dug tunnels in search of the "black gold" of the San Joaquin. These mines were located just outside of McKittrick, a pioneer town that sprang up near the old Asphalto tar pits. Generally, McKittrick asphalt was used to pave streets and sidewalks in San Francisco or to grease log skids in the timber country.
Gradually, the tar mines were replaced by wells that drilled for the same oil which sourced the tar seeps. A new chapter began in when the Shamrock gusher blew in at McKittrick field flowing 1, barrels of oil per day. Additional discoveries gave rise to nearby Midway-Sunset field, which today is one of the giant oil fields of the United States.
Ultimately, the McKittrick and Midway-Sunset areas together are expected to produce some 3 billion barrels of oil. Photo of a tar pit. Entrance to an asphalt mine. Modern tar pit near McKittrick.
Entrance of a tar shaft.La Brea Tar Pits Geology Reference List Tanya Atwater’s tectonics and geologic history animations: attheheels.com The La Brea “tar pits,” discovered on August 3, , by Spanish explorer Gaspar de Portola, exemplify the many natural oil seeps of southern California.
LA Basin Science attheheels.com The La Brea Tar Pits are a group of tar pits around which Hancock Park was formed in urban Los Angeles. Natural asphalt (also called asphaltum, bitumen, pitch or tar—brea in Spanish) has seeped up from the ground in this area for tens of thousands of years.
The tar is often covered with dust, leaves, or attheheels.comon: Hancock Park, Los Angeles. The Rancho La Brea Tar Pits is one of the world's most famous fossil localities, located 5 miles west of downtown Los Angeles.
Near the end of the Ice Age—about 40, to 10, years ago—saber-toothed cats, Columbian mammoths, American mastodons, and dire wolves roamed the Los Angeles Basin. LA Basin Science attheheels.com