Joyce Allen, age 8 of Lakewood, Ohio for her question:

What is tar?

Did you wonder why a dark night is called pitch black? It means that the night is dark as pitch ‑ no moon, no stars. And pitch is another name for tar. Asphalt is also another name for tar. Nature makes great pools of asphalt ‑ dark brown or midnight black. Men have also learned how to make tar. Man‑made tars are used to make dyes and medicines. And, of course, many roads are paved with asphalt.

Nature takes a long time to make her pools of asphalt. She brews them in the same places for millions of years. There are tar pits near the Dead Sea and in the East and West Indies, But the most famous tar pit in the world is near Los Angeles, California. This tar pit has kept a diary of who lived in America for 100,000 years.

Nature’s tar is sticky stuff. It usually forms from rock oil near the surface of the ground. Rock oil is petroleum trapped in the pores of rocks. Air and sunshine evaporate some of the lighter particles of the oil. Asphalt is left behind. The black, gooey stuff oozes up from small holes in the ground. In flows over into dark, glossy pools.

In time, the outer edges of the pool harden to look like coal.

The Spanish discovered the tar pits near Los Angeles. Their name for this hardened asphalt was brea. The famous tar pit that kept a diary of ancient Americans is called Rancho La Brea. And this is how the diary was kept.

The pool of sticky tar shone like wet water. A thirsty animal came along, hoping for a drink. Before he knew it, he was held there fast in the sticky mess. He cried out for help. Instead of help, the vultures acid the meat‑eating animals pounced down to feed upon him. All were trapped. All sank down into the sticky tar. Their bones were preserved to make fossils.

The asphalt from this pit was dug to make roads. The bones of these old American animals came to light. Experts put them together and gave us a picture of the animals that lived here 100,000 years ago. There were lions, bigger than any lion living today. There were sabre tooth tigers with teeth a foot long, they were giant ancestors of the elephant. There were horses, camels and llamas. These creatures no longer live here. But the diary of the tar pit proves that once they did.

Tar can be soft, brittle or plastic. It is mixed with harder materials to make roads, but sometimes a hot day makes it tacky. It may stick to your shoes. It won’t wash off with water. But it will dissolve and rub off with gasoline. Maybe you are lucky to get off with a bit of tar on a shoe. At least you didn't fall into a pool like the lost sabre‑tooth tigers,