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Geologic Time

Geologic Time. An Introduction. Linda Kennedy, Department of Geography, UNCG, July 2011. Geologic Time there’s just so much of it!. Earth is how old?

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Geologic Time

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  1. Geologic Time An Introduction Linda Kennedy, Department of Geography, UNCG, July 2011

  2. Geologic Time there’s just so much of it! Earth is how old? Our planet formed approximately 4.5 billion years ago (4,500,000,000). Geologists divide this immense length of time into progressively smaller (and more manageable) units of time using fossils, radiometric dating, and rock sequences. We will discuss the major characteristics of the Precambrian, Paleozoic, Mesozoic, and Cenozoic eras.

  3. Geologic Time there’s just so much of it! History written in stone Evidence from rocks allows geologists: To identify the geological processes that resulted in the formation of each rock. http://www.abdn.ac.ukhttp://news.nationalgeographic.comhttp://events.ucr.edu To reconstruct plant/and or animal life prevalent during the formation of rocks. http://dinobase.gly.bris.ac.uk To reconstruct atmospheric/climatic conditions and changes through time. http://uts.cc.utexas.eduhttp://nsidc.org

  4. Geologic Time there’s just so much of it! It is very difficult for humans to conceptualize a time frame as large as 4,500,000,000 years. To help we will imagine that Earth formed at 9:00 am this morning and it is now only10:00 am. What has occurred on planet Earth during the past hour? Present

  5. The Precambrian Era 4.5 billion – 570 million years ago Precambrian 9:00 – 9:53

  6. The Precambrian Era 4.5 billion – 570 million years ago Most of the past hour – 53 minutes –is known as the Precambrian era. Earth’s crust formed at approximately 9:01 but much of it has been recycled or altered from it’s original state (metamorphosed). Precambrian rock in North Carolina is located in the western portion of the state, in the Blue Ridge Mountains and includes granites, gneisses, and schists. Granite is magma that cooled deep in the crust and schist and gneiss are examples of rocks that have been heated and pressurized, altering their original form. Life during the Precambrian included single-celled, and simple multi-celled organisms.

  7. The Precambrian Era 4.5 billion – 570 million years ago Banded iron is believed to have formed when oxygen released by blue green algae combined with iron present in ancient ocean waters to form iron oxide precipitates that settled to the ocean floor. Stromatolites are dome shaped mineral formations built by microbes. They continue to survive today in the waters around Australia. Fossil stromatolites are one of the most common forms of fossil life identified in Precambrian rocks. http://www.eps.mcgill.edu http://gsc.nrcan.gc.ca/paleochron/03_e.php http://gsc.nrcan.gc.ca/paleochron/03_e.php

  8. The Precambrian Era 4.5 billion – 570 million years ago Rock formed during the Precambrian is a valuable resource in North Carolina Mount Airy, Surry Co. The world’s largest open faced granite mine. The granite formed when magma cooled deep in the crust. Overlying rock has since been eroded away, exposing the granite. Mica North Carolina is the nations top producer of mica, a mineral used in a variety of industries. http://ncpedia.org/symbols/rock http://www.minfind.com

  9. The Paleozoic Era “old life” 570 – 245 million years ago Paleozoic 9:53 – 9:56.9

  10. The Paleozoic Era “old life” 570 – 245 million years ago If all of Earth’s geologic history is represented by one hour then the Paleozoic era occurred between 9:53 am and 9:56.9 am. The Paleozoic is characterized by the development of diverse sea life and the emergence of the first land plants, first insects, first amphibians, and first retiles. The end of the Paleozoic is marked by a mass extinction of life on Earth. Rocks formed during the Paleozoic are located in a SW-NE trending belt in central North Carolina, and are characterized by intrusive and extrusive volcanic rocks, and metamorphosed sedimentary deposits.

  11. The Paleozoic Era “old life” 570 – 245 million years ago Life

  12. The Paleozoic Era “old life” 570 – 245 million years ago Mississippian: First reptiles http://www.bluesci.org Devonian: First amphibians http://www.exploratorium.edu Labidosaurus hamatus Ichthyostega Silurian: First fish & land plants http://tolweb.orghttp://ww.cavehill.uwi.edu Ordovician: Crinoids & Starfish http://www.oum.ox.ac.uk http://museumvictoria.com.au Cambrian: Trilobites & Sponges http://www.fossilmuseum.net http://www.palaentology.geo.uu.se

  13. The Paleozoic Era “old life” 570 – 245 million years ago Rock formed during the Paleozoic is a valuable resource in North Carolina Metamorphic, sedimentary and igneous rocks of Paleozoic age are quarried throughout North Carolina, including the High Point area, for use in a variety of construction projects. http://www.wakestonecorp.com

  14. The Mesozoic Era “middle life” 245 – 70 million years ago Mesozoic 9:56.9 – 9:58.7

  15. The Mesozoic Era “middle life” 245 – 70 million years ago The Mesozoic era occurred between 9:56.9 am and 9:57.8 am. During this brief 1.8 seconds, the dinosaurs came and went, and the first birds and mammals emerged. The end of the Mesozoic, like the Paleozoic before it, was marked by a mass extinction. Mesozoic rocks occur principally in southeastern North Carolina, and are characterized by sedimentary deposits of sandstone, shale, and clays.

  16. The Mesozoic Era “middle life” 245 – 70 million years ago Life

  17. The Mesozoic Era “middle life” 245 – 70 million years ago Cretaceous: T-Rex and Triceratops http://www.impactlab.nethttp://www.itsnature.org Jurassic: Archaeopteryx, Stegasaurus and first flowering plant http://www.itsnature.orghttp://www.askabiologist.org.ukhttp://news.ufl.edu Triassic: early dinosaurs and turtles http://news.bbc.co.ukhttp://www.nmnaturalhistory.org

  18. The Mesozoic Era “middle life” 245 – 70 million years ago Deposits formed during the Mesozoic are a valuable resource in North Carolina Sand and gravel extraction is the largest income producing mining in North Carolina. http://www.boggspaving.com

  19. The Cenozoic Era “new life” 70 million years ago – present Cenozoic 9:58.7 – 10:00

  20. The Cenozoic Era “new life” 70 million years ago - present It is only during the last 1.3 seconds that the first human ancestor appeared, ice ages occurred, and modern man evolved. Unconsolidated sands and clays of the Coastal Plain date to the Cenozoic era.

  21. The Cenozoic Era “new life” 70 million years ago – present Climate ameliorates 10,000 years ago, allowing the development of agriculture and human civilization. http://www.gsi.ie Mammals dominate land, human evolution occurs. http://www.dailymail.uk.co

  22. The Cenozoic Era “new life” 70 million years ago – present Deposits formed during the Cenozoic are a valuable resource in North Carolina Aurora, N.C. Phosphate mine. North Carolina is the nations second largest producer of phosphate. North Carolina and Florida account for 95% of the total phosphate produced in the U.S. http://www.wazengineeriing.com

  23. Resources General N.C. Department of Environment and Natural Resources http://portal.ncdenr.org United States Geological Survey (USGS) http://www.usgs.gov N.C. Geological Survey http://www.geology.enr.state.nc.us USGS Studies in N.C. http://pubs.usgs.gov/fs/fs-033-96 Relief Map of North Carolina http://geology.com/shaded-relief/southeast.shtml Lesson plans/Activities Geosphere links for teachers http://nesen.unl.edu/scienceresources/linksgepsphere.asp Resources for K-12 Earth Science Educators http://www.geosociety.org/educate/resources.htm USGS resources for secondary schools http://education.usgs.gov/common/secondary.htm Mining Institute http://www.mii.org

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