The Tertiary in Colorado, US |
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Paleontology and geologyDuring the Tertiary, the Rocky Mountains rose, began to erode, and were buried in their own debris. Tropical rainforests grew along the eastern slopes of the young Rockies in the Early Tertiary, and volcanoes rose, shedding debris and ash into the Denver Basin. Mammals, crocodiles, and turtles are the most common animal fossils from these areas. In northwestern Colorado, uplift of the mountains left low-lying areas between the ridges, which filled with water to form huge lakes. Algae accumulated with the lake bottom mud to form oil shales that are the source of fossil fish, leaves, and insects. Cooling later in the Early Tertiary (late Eocene) encouraged the growth of Sequoia forests in the Rockies. Mudflows near Florissant (central Colorado) preserved standing trunks of these huge trees. Large volcanic eruptions in the southern half of the state in the Early to Mid-Tertiary (late Eocene and Oligocene) formed the core of the San Juan Mountains. Ash from these eruptions covered the eastern portion of the state and preserved a variety of mammal fossils, including titanotheres, rhinos, giant pigs, gomphotheres, and bear dogs, to name but a few. Grasslands appeared across much of the state near the end of the Tertiary. |
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Links to more on the Tertiary in Colorado |
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