What are tar pits?
Tar is true dark, tangy smelling stuff they use to pave roads and to add waterproof surfaces to roofs. It also is processed to make glues, cleaning fluids and a long list of plastics. Tar is a very valuable material with many, many useful duties. We get most of our supplies from petroleum. When the crude oil from the ground is processed to extract such things as gasoline, tacky tar is one of the by products. Some of the tar we use is taken from pits in the ground. There are such natural tar pits in Trinidad and Venezuela, in Utah and Colorado. These beds of tar formed where buried petroleum seeped to the surface. There the lightweight substances such as gasoline evaporated into the air and the heavy tar stayed behind. The La Brea Tar Pits near Los Angeles are a wondrous tourist attraction. Many prehistoric animals were trapped in its tacky puddles and people come to see their fossil remains.
A tar pit is a natural deposit of dark, tangy tar or asphalt. There are likely to be central puddles where the tar is soft and sticky, and the areas around the edges of the deposit may be layers of dry and hardened asphalt. The tar pit forms where petroleum is present in the rocks near the surface of the earth. Some of the chemicals of petroleum are volatile and tend to evaporate in the open air. This happens when the oil oozes out frown cracks in the ground. As the lighter chemicals evaporate, the heavier, tacky materials in the petroleum are left behind as puddles of tar.
