The La Brea Tar Pits, situated in the middle of Hancock Park in Los Angeles, are a petroleum reservoir on the southern edge of the Salt Lake Oil Field.
Working oil wells are scattered throughout the area, hidden in plain sight. Bitumen oozes and bubbles to the surface daily and traps any animals that make their way into the thick tar pits by mistake.
Bitumen also occasionally makes its way into nearby sewers, sidewalks and basements, straying from the confines of the park that was donated to the city by Captain G. Allan Hancock.
The pits were formed by crude oil seeping through fissures in the Earth's crust and evaporating into the air, leaving bitumen on the surface. The smell of aromatic hydrocarbons lingers in the air, noticeable from the nearby busy intersection of Wilshire and Beverly, and gets stronger the closer you get to the largest pit where replicas of wooly mammoths appear to be stuck in time, one half submerged in the pit. The replicas are a reminder of reality, as the pits still contain the remains of many animals that have been caught in the bitumen over time.
LaBrea Tar Pits with wooly mammoth replica stuck in Tar: