Learn about the fossils trapped in tar in Rancho La Brea and learn ten new words in the context of this word power story with interactive exercises and an exclusive PDF practice worksheet for my patrons. The word for this episode are congestion, encompass, congeal, immerse, demise, pervade, excavate, fervid, confute, and probe.
Fossils Trapped in Tar
Not far from the congestion of the Los Angeles freeways, sabretooth cats, mastodons, and giant ground sloths once roamed the land. During the Ice Age, which encompassed a period of time some 10,000 to 40,000 years ago, over 400 different kinds of animals lived on the grassy plain that is now Los Angeles.
Then, as now, large deposits of oil lay beneath the earth in California. When these deposits seeped through the cracks in the surface, the oil evaporated, leaving pools of sticky tar that would catch leaves and other forms of ground cover. During colder weather, these pools congealed, trapping the leaves in the hardened tar. Then in the summer heat the tar pools beneath the leaves softened into an ooze similar to molasses. Unsuspecting animals walked into the ooze and sank. Once these beasts became immersed in the tar, it was nearly impossible for them to escape. These oily tar pits caused the demise of thousands of animals. The animals’ remains did not vanish, however. The same tar that caused their deaths also pervaded their bones and preserved them as fossils.
Until 1906, the tar from Rancho La Brea was excavated for use as a glue. It was then that Dr. John C. Merriam, at the University of California, realized the importance of the fossils that were being dug up along with the tar. After that, scientists began the fervid excavation of these revealing fossils. Evidence of mammoths, mastodons, saber-tooth cats, lions, wolves, sloths, camels, horses, and other animals was uncovered.
In 1977 the fossils were placed in a museum and research center. There paleontologists study bone fossils, which tell of events that took place thousands of years ago and try to explain why the animals became extinct. One theory is that they were overhunted by early humans. While it is difficult to confute this theory, some scientists question why the bones of only one human have been found in the Rancho La Brea tar pits. As scientists continue to probe for answers, their discoveries about the past may help us glimpse the future.
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