Falling into a tar pit initiates a unique and dangerous struggle against the laws of physics. A tar pit is not a pool of liquid oil, but a naturally occurring deposit of asphalt, also known as bitumen, which has seeped up from underground petroleum reservoirs. Over long periods, the lighter, more volatile components of the crude oil evaporate into the atmosphere, leaving behind a thick, sticky, semi-solid residue. The world-famous La Brea Tar Pits in Los Angeles serve as a historical example of these geological formations, acting as natural traps.
The Physics of Entrapment
The primary danger of a tar pit lies in the material’s extreme viscosity, which is a measure of its resistance to flow. Natural asphalt can be hundreds of millions of times more viscous than water, making any movement within it nearly impossible. This material is also viscoelastic, meaning it resists rapid force like a solid, yet will slowly deform under constant pressure.
The adhesion, or “stickiness,” of the bitumen acts like an industrial-strength cement, gripping the surface of the skin and clothing. Attempting to pull a submerged leg free requires not only overcoming the viscous drag but also the adhesive forces attempting to keep the limb sealed within the material. Even a slight decrease in ambient temperature can significantly increase the asphalt’s resistance, effectively transforming the material into an immovable, rock-like substance.
Immediate Hazards and Physical Struggle
The instinct to struggle upon falling into a tar pit quickly becomes the greatest hazard to survival. Any attempt to move a limb rapidly is met with massive resistance, a direct application of physics where the drag force is proportional to the speed of movement. This cycle of frantic movement and intense resistance leads to almost immediate and debilitating physical exhaustion.
As the person struggles, the dense asphalt begins to cover more of the body, allowing them to sink further into the material. If the bitumen reaches the torso and chest, it can restrict the ability of the lungs to expand, leading to positional asphyxiation. The external pressure from the dense material prevents the muscular efforts required for inhalation, severely limiting oxygen intake. If the pit is covered by a layer of water, a common occurrence in natural seeps, the added element of cold water exposure can rapidly induce hypothermia.
Challenges of Rescue and Extraction
The unique physical properties of the asphalt create extreme difficulty for any attempted rescue. Extracting a person requires overcoming the immense viscous and adhesive forces that anchor the body in place. The force needed to pull a fully trapped adult free can easily exceed the tensile strength of human joints and limbs, meaning that a direct pull risks serious, catastrophic injury.
Rescuers must employ specialized techniques and equipment, similar to those used in confined space or industrial recovery operations. This often involves using wide-surface harnesses and webbing to distribute the load across the victim’s body, preventing injury during extraction. Specialized gear, such as mechanical advantage systems or high-pressure solvents, may be necessary to reduce the asphalt’s viscosity or lubricate the interface between the body and the material. Furthermore, the ground around the pit is often unstable, posing a severe risk that rescuers themselves could become trapped.
Preservation of Remains
If a body or organism is completely enveloped by the asphalt, the material acts as a unique preservative. The dense bitumen seals the remains off from the outside world, creating an anoxic, or oxygen-free, environment. This absence of oxygen inhibits the microbial action of bacteria and fungi, which are the primary agents of decomposition.
While the soft tissues typically decay before full submersion, the bones are effectively embalmed. The asphalt permeates the porous structure of the skeletal remains, staining them a dark brown or black color and protecting them from erosion and chemical weathering. Tar pits become invaluable archives, preserving not only the bones of large mammals but also tiny microfossils, such as pollen grains, insects, and plant remnants, offering a detailed record of ancient ecosystems.