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Learn about the geologic history of Texas, from plate tectonics and Texas geography to major Texas events and the principles of geologic time. This educational CD-ROM presentation by Dr. Richard Kyle provides a comprehensive overview of Texas' geologic past and is a valuable resource for students and enthusiasts alike. (498 characters)
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Geologic History of Texas:The Making of Texas Over 1.5 Billion Years # 4 Dr. Richard Kyle March 24, 2000 Produced by and for Hot Science - Cool Talks by the Environmental Science Institute. We request that the use of these materials include an acknowledgement of the presenter and Hot Science - Cool Talks by the Environmental Science Institute at UT Austin. We hope you find these materials educational and enjoyable.
Geologic History of Texas: The Making of Texas over 1.5 Billion Years Geologic History of Texas: The Making of Texas over 1.5 Billion Years J. Richard Kyle Department of Geological Sciences The University of Texas at Austin
Acknowledgments I am grateful to many individuals who have contributed to my understanding of the geologic history of Texas, particularly present and former colleagues at The University of Texas at Austin in the Department of Geological Sciences, the Bureau of Economic Geology, the Institute for Geophysics, and the Texas Memorial Museum. These individuals and institutions have contributed many of the illustrative materials contained in this CD-ROM. The presentation contained herein was made by J. Richard Kyle and is intended for educational purposes only. Any use of this work, partial or complete, must cite J. Richard Kyle and this Outreach Lecture Series Volume 4. No portion of this product may be reproduced or distributed in any form. March 2000
Texas Geography Austin
Texas Geology Austin
Geologic Time Principles 8. Geologic Time Principles Several geologic principles are fundamental to using the rock record to interpret processes. Original Horizontality: Most rocks that form at the Earth's surface are deposited in essentially horizontal layers. Therefore, when layered rocks are not horizontal, they probably have been affected by post-depositional processes such as a tectonic event. Superposition: When layered rocks are formed, they are deposited in an orderly sequence with the oldest being at the base of the sequence and the strata becoming progressively younger upward. Therefore when a sequence of rocks differs from the predicted sequence, or layers are missing, then an explanation for the cause of these differences is required. Cross-cutting Relationships: Features such as faults or igneous intrusions generally cross-cut or affect all rocks that were present locally at the time of the faulting or intrusive event. Uniformitarianism:Present Earth processes are useful in understanding the types and rates of processes that have affected the Earth during past periods of geologic history.
Time Interpretation Based on Llano Stratigraphic Column Erosion D Mesozoic Erosion C Erosion Paleozoic B Erosion Protero- zoic A Geologic Time 0 Ma 200 Llano rocks D 400 B C 600 A 800 1000 1200 1400
Deformed metamorphic rocks cut by granite dike Intrusive dike crosscutting folded metamorphic rocks.
Tectonic Model for the Precambrian History of the Llano Region
Himalayas Tibet Plateau Himalayas India
Great Barrier Reef, eastern Australia Tree Covered Island Bird
Marathon map Marathon Uplift
Marathon exposures Flat-lying Cretaceous Limestones Dip direction Haymond Formation
Permian Basin filling by Evaporites OPEN OCEAN
Death Valley, California Volcano Salt Lake
Cretaceous Limestone Exposures along the Colorado River in Austin
Cretaceous Volcanoes in Central and South Texas Pilot Knob Uvalde area