Reference no: EM133561922

Question: Ranch La Brea is the best preserved ice-age ecosystem on Earth. Millions of specimens of hundreds of species of mammals, birds, reptiles, invertebrates, plants and other organisms have been recovered here.

The Rancho La Brea (RLB) deposits formed when cracks in the earth (e.g., faults) allowed low-grade petroleum to percolate to Earth's surface, which was composed of soft marine sand. At the surface, volatile components of the petroleum escaped, leaving behind the more viscous asphalt. Many of these vents emerged in areas of ponded water, where it was largely invisible to animals at the water's edge. Some animals became entrapped in the sticky asphalt, and their cries or decaying corpses beckoned to predators and scavengers, who, in turn, became entrapped themselves.

First excavations at Rancho La Brea began in March 1906. Since then, millions of Late Pleistocene fossils have been discovered here. Hancock Park was donated in 1915 to the city of Los Angeles, with the understanding that it would be preserved as a landmark of unparalleled scientific value. It is one of the few museums where the fossil specimens are housed and displayed at the location where they were discovered.

The "tar pits" get their name from pits that people dug to excavate the fossils. Each of the numbered circles on the map at right shows a pit from which a significant number of fossils were extracted.