Prelude
Earth's geologic history witnessed significant changes at the beginning of the Paleozoic Era. The sudden appearance of abundant fossilized shells and exoskeletons record the diversification of life forms that occurred exclusively in Earth's oceans. Trilobites, brachiopods, corals, sponges, etc. are all abundant in Early Paleozoic marine rocks, but primitive life encroached onto land much later. Plate tectonic processes continued through the Early Paleozoic, forming volcanic and tectonic mountain ranges, subduction zones, etc. The ancient cores of Australia, Africa, and South America formed Earth's largest continental mass, Gondwana, and Panthalassa was Earth's largest ocean. Laurentia remained isolated near Earth's equator, and sedimentary rock units exposed in the Grand Canyon record a part of this geologic history.
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Figure 10-1. Early Paleozoic mysteries of the Grand Canyon. At left, Cambrian and Devonian rocks form the lower gorge in the stretch between Havasu Canyon and Tuckup Canyon (Colorado River mile 160). Strolling into National Canyon (center; Colorado River mile 166.5), where the Muav Limestone and Temple Butte Limestone are exposed below the Redwall Limestone. A waterfall in the Muav Limestone of the upper narrows of Saddle Canyon (Colorado River mile 47.1). Remember to click on the highlighted images to see larger versions. |
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What Will You Do Today?
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Explore the geologic history of the Early Paleozoic Era, including the Cambrian, Ordovician, Silurian, and Devonian Periods |
A. The Early Paleozoic Era - Review Early Paleozoic geologic time
B. Early Paleozoic Geology & Life Forms - Learn about the geology, tectonics, impact events, life forms, etc. of the Early Paleozoic Era
C. Appalachian Mountains & Grand Canyon Geology - Explore the Early Paleozoic geology of the Appalachian Mountains and Grand Canyon areas
D. Geology of the Cheops Pyramid Area - Study a sequence diagram of the Cheops Pyramid area of the Grand Canyon