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| What is asphalt? |
| Asphalt is the lowest grade of crude oil. At Rancho La Brea, asphalt is the residue left on the surface of the ground as the lighter elements of crude oil (such as kerosene) evaporate into the atmosphere. Copious amounts of asphalt are produced as a by-product of gasoline refining. This heavy, viscous substance is commonly called tar; however, this is misleading. Tar is a by-product of destructive distillation of woody materials, such as coal or peat. |
| Where does the asphalt come from? |
| A large petroleum reservoir called the Salt Lake Oil Field is located below the surface a short distance to the north of Hancock Park. The oil was formed from marine plankton deposited in an ocean basin during the Miocene Epoch (5-25 million years ago). Time and pressure converted the organisms into oil. For about 40, 000 years, this petroleum has been migrating to the surface, either along a faulted sedimentary zone or along steeply dipping, porous sedimentary rock layers. |
| Are the asphalt seeps restricted to the pits in Hancock Park? |
| Although large quantities of asphalt comes up in the former excavation pits, visitors can also observe asphalt seeping onto the surface of the ground outside the fenced areas. In fact, asphalt seepage is not restricted to Hancock Park. For several blocks in all directions, asphalt has been found seeping onto surface streets, into sewers and under buildings. |
| Can the asphalt from Rancho La Brea be purchased? |
| The asphalt is not available for sale. Free samples will be provided to qualified research professionals and students upon request to the Collection Manager of the Page Museum. |
| What causes the bubbling in the Lake Pit? |
| The bubbles seen in the Lake Pit and at other pit sites are composed of methane, commonly called as natural gas, escaping into the atmosphere. Methane gas, which is colorless and odorless, is the same substance used in gas-burning home appliances (the gas company adds an odor for safety reasons). Methane is a by-product created when plant and animal remains decompose with the formation of crude oil. The "rotten egg" odor is hydrogen sulfide, another by-product of decomposition. |
| Who was G. Allan Hancock? |
| Captain George Allan Hancock inherited 4,400 acres of land which comprised the original Mexican land grant called Rancho La Brea from his father, Major Henry Hancock. The Hancock family owned and operated a refinery at Rancho La Brea between 1870 and 1890, commercially mining and exporting asphalt to local markets. At the turn of the 20th century, the Hancocks become wealthy with the onset of the oil boom in southern California. A businessman, railroad man, rancher, marine scientist and patron of the arts, G. Allan Hancock donated the 23 acres of Hancock Park to Los Angeles County in 1916 to preserve and exhibit the fossils exhumed from Rancho La Brea. Hancock's parents, Henry and Ida, at one time lived in a house that was located adjacent to what is today the park's Lake Pit. |
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