Nature
Rainbow Basin in the Calico Peaks north of Barstow, California, is a protected desert landscape where vividly colored, folded rock layers and eroded badlands reveal a long geologic history. Sediments laid over an older quartz monzonite foundation were later compressed, uplifted, folded, and faulted, creating formations such as the Barstow Syncline. Its three main sedimentary units include the fossil-rich Barstow Formation, which preserves one of North America’s largest Cenozoic fossil assemblages, including camels, horses, mastodons, and flamingos once absent from modern California. In 1941, the site became the type reference for the Barstovian Land Mammal age, securing its lasting scientific importance.
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California · United States
