Mary Kate Morgan, age 12, of Philadelphia, Pennsylvania for her question:

What are the La Brea pits?

In a park surrounded by the modern city of Los Angeles, there is a place that takes you back to the ice ages. No, it is not a remnant of an ancient glacier. It is a place where gooy petroleum oozes to the surface and evaporates, leaving puddles and soggy pockets of tacky tar. It has been there for ages and for ages the local animals have mistaken its shiny puddles for water holes. Into the sticky stuff they stepped—and were trapped.

The sticky tar pits were there during the last ice age, when all sorts of prehistoric animals roamed this region of Southern California. Countless numbers were trapped in the gummy tar when they came to investi¬gate what looked like shiny water. Their bones were preserved and fossil¬ized in the tacky mire. They include the remains of giant wolves and giant ground sloths, of llamas and camels and horses, of huge vultures and menacing saber toothed tigers. The reconstruction of their fossil skeletons takes us back to the ice ages