!!!!! STOP!!!!! What is environmental geology?

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3 !!!!! STOP!!!!! What is environmental geology? Geology Study of rocks and minerals that comprise earth s surface and interior and the natural processes that shape the earth s surface and interior over all time scales. Environmental Geology Study of interactions and feedbacks between people, geologic processes, and geologic materials. Environmental geologists are in some sense applied geologists they bring collective geologic knowledge to bear on problems important to people.

4 Earth as a closed system implies nearly everything is cycled, recycled Population: 6.2 billion in 2002 Growth rate: 1.2% 49 poorest countries: 2.4% Industrial countries: 0.25%

5 Are the earth s resources really infinite, as this writer implies? If they are, then why conserve anything? A man with a political agenda: manipulating the numbers

6 Can global grain production keep up with population? Since Y2000, it has not and grain stocks have been drawn down to multi-decade lows. Course Information Everything you need to know is on the course web site:

7 Course Overview I. Fundamentals: Minerals and Rocks Plate Tectonics Basic Vocabulary of Geology Foundations and Building Materials Important Natural Resources Impacts on Human Health Unified theory that explains distribution of mountain belts, deep sea trenches, earthquakes, volcanoes, and the rock cycle II. Natural hazards resulting from internal and surface processes: Earthquakes, volcanic eruptions, landslides Above: landslide onto Gokuna glacier triggered by 11/03/02 Denali M=7.9 EQ Left: Pyroclastic flow during 1991 eruption of Mt. Uzu, Japan

8 III. Additional surface processes: Streams, coasts, glaciers and deserts IV. Resources Water, Minerals, Energy

9 V. Waste Disposal, Pollution and Health Get your CPS clickers ready if you have already registered them

10 Earth and other planets in the solar system formed A. Approximately 6000 years ago B million years ago C. Approximately 100 million years ago D. Over 4.5 billion years ago Example participation question Environmental Significance of Geologic Time Perspectives on rates of natural processes and human impacts Rising and falling of tides - 1 day Drift of continents by 3 cm - 1 year Recurrence of large earthquakes on a major fault - 10s to 100s of years Deposition of 1 cm of sediment on the seafloor yrs Advance and retreat of ice sheets - 10,000 to 100,000 yrs Life span of a large volcano - 1 to 10 million yrs

11 How do we determine the age of the Earth? (see Appendix A) Relative Dating Qualitative answer only Order of Events: (for figure below) 1) deposition of limestone and shale, 2) basalt intrusion, 3) tilting, 4) erosion, 5) deposition of sandstone, 6) lava flow Correlation: similar fossils indicate strata deposited at similar times in the past, faunal succession over time + Uniformitarianism: similar geologic processes in the past as we observe today Rate of Heat Loss: Estimate of million years by British physicist Lord Kelvin in late 1800s Age of the Earth (continued) Quantitative estimates Incorrect because didn t account for radioactive decay which adds heat Salt in the oceans: Irish physicist John Joly, in 1899, assumed pure water at start, and estimated how long it would take for rivers to deliver salt from erosion of rocks. Estimate of 100 million years did not consider varying rates of weathering or removal of salt by formation of evaporite rocks

12 Age of the Earth (continued) Quantitative estimates Radiometric Dating: Measures of concentrations of parent and daughter isotopes in a rock used to determine rock age. Meteorites and moon rocks yield ages of about 4.5 billion years Earth and other planets in the solar system formed A. Approximately 6000 years ago: 17 th century estimate by Ussher on basis of generations in the Bible B million years ago: 19 th century estimate by Kelvin on basis of heat loss C. Approximately 100 million years ago: 1899 estimate by Joly on basis of salt in the ocean D. Over 4.5 billion years ago: current estimate based on radiometric dating of meteorites and moon rocks

13 If Earth s history is equated to a 24- hour day, approximately when did modern humans (homo sapiens) arrive on the scene? A.1 hour ago B. 10 minutes ago C. 1 minute ago D. 10 seconds ago E. 1 second ago 1 hour 190 million years 1 minute 3 million years Another participation question will be repeated for credit during the next lecture