Tar pits, often referred to more accurately as asphalt pits, are natural geological formations consisting of large deposits of asphalt. These pits form when crude oil, created from decayed organic matter subjected to underground pressure, seeps upward through fissures or porous rock layers. As the crude oil reaches the Earth’s surface, its lighter, more volatile components evaporate into the atmosphere. This process leaves behind a dense, black, and highly viscous substance known as asphalt, which accumulates in depressions, forming the sticky traps.
The Immediate Danger
Falling into a tar pit presents immediate and severe physical challenges. The asphalt’s high density and extreme stickiness cause rapid entrapment, making movement exceptionally difficult. As a person or animal struggles, they become immobilized, sinking deeper into the viscous material. This struggle quickly leads to exhaustion due to the immense effort required.
Prolonged exposure also brings risks of dehydration and potential suffocation if the asphalt level rises above the chest or if noxious gases are present. Struggling prey can attract predators, which may then become trapped themselves.
The Science of the Trap
The danger of tar pits stems from asphalt’s unique physical properties. Asphalt possesses high viscosity, meaning it resists flow, and strong adhesive qualities, causing it to cling tightly to anything it contacts. This combination makes it difficult for a trapped individual to pull free, as struggling further entangles them.
The density of asphalt also contributes to sinking, though it acts more like a flypaper than quicksand, gradually immobilizing rather than rapidly engulfing. Temperature affects asphalt’s consistency; warmer conditions make it softer and stickier, increasing its trapping efficiency. Additionally, a thin layer of water, dust, or leaves can often obscure the asphalt’s surface, making these treacherous areas appear deceptively solid or like appealing watering holes.
Preservation Through Time
Beyond immediate peril, tar pits serve as exceptional natural preservers of organic remains. The asphalt’s anaerobic environment, lacking oxygen and water, inhibits decomposition by preventing bacterial and fungal activity. This quality leads to the fossilization of bones and other hard tissues, offering a window into ancient ecosystems.
The La Brea Tar Pits in Los Angeles, California, exemplify this, yielding millions of specimens over tens of thousands of years. These fossil collections include large mammals like dire wolves and saber-toothed cats, as well as microfossils such as wood, plant remnants, insects, and pollen grains, providing detailed insights into prehistoric life and climates.