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Introduction to Earth Science/Geology C. Ophardt

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1 Introduction to Earth Science/Geology C. Ophardt
Geology, What is it? Geology is the study of the Earth. Includes surface process which have shaped the earth's surface Study of the ocean floors Interior of the Earth. History of the Earth as it has evolved to its present condition. The Earth has changed throughout its history, and will continue to change (Unifying Theme)

2 Earth Science/Geology - Time Scale
Time scale (Unifying Theme) Earth is about 4.6 billion years old Human beings - maybe 2 million years. Humans have witnessed only 0.043% of Earth history How can we think about changes on earth on a scale of billions of years?

3 Earth Science/Geology - Time Scale II
Try to imagine 1 million years That's 50,000 times longer than you have lived. A river deposits about 1 mm of sediment (mud) each year. How thick is the mud after 100 years?  -- 10 cm hardly noticeable over your lifetime. What if the river keeps depositing 1 mm/yr  for 10 million years?       Answer 10,000 meters (6.2 miles).

4 Scientific Method - Inquiry in Earth Science
Strongly tied to experiment and observation. Observations can be cast as experiments -- thought experiments. Observation: Wind River Mountains in Wyoming - 10,000 feet above sea level -observe a rock containing many seashells. How did it get there?

5 Scientific Method - Inquiry in Earth Science
Questions: Was area covered by an ocean at some time in the past? Was this ocean 10,000 feet deep? Was this area at one time at sea level and unknown forces elevated it to its present elevation? Tie in to previous slide about rate of deposition.

6 Inquiry in Earth Science III
Hypothesis: The observation leads to several hypotheses Attempt to explain the observation. Formulation of a tentative explanation is not sufficient What additional information may be needed in order to "prove" the hypothesis? New information may modify the original explanation or cause it to be discarded.

7 Inquiry in Earth Science IV
Theory: Principle of Uniformitarianism - Slow Changes Processes that are operating at present are the same processes that have operated in the past. “Present is the key to the past.” Look at processes that occur today,   Infer that the same processes operated in the past. Key Assumption - Laws of nature have not changed through time.

8 Inquiry in Earth Science IV
Theory: Principle of Catastrophism: - Fast Changes Major changes in Earth’s crustal layers result from catastrophic events Floods Massive Volcanism Massive Earthquakes Changes were sporadic Key Assumption - Laws of nature are the same but the rate of change is not

9 Earth Materials and Processes
Slow processes Formation of rocks Chemical breakdown of rock to form soil (weathering) Chemical cementation of sand grains together to form rock (diagenesis) Recrystallization to rock to form a different rock (metamorphism) Build mountain ranges (tectonism) Erosion of mountain ranges

10 Earth Materials and Processes
Fast Processes Beach erosion during a storm. Construction of a volcanic cone Landslides (avalanches) Dust Storms Mudflows Earthquakes

11 Structure of the Earth Crust - variable thickness and composition
Continental km thick Oceanic km thick Mantle km thick, made up of a rock called peridotite Core km radius, made up of Iron (Fe) and small amount of Nickel (Ni)

12 Structure of the Earth

13 Structure of the Earth- Hydrosphere
Water sphere includes all the earth's water found in streams, lakes, the soil, groundwater, and in the air. Water of hydrosphere is distributed: oceans, lakes, streams. Water is found in vapor, liquid and solid states in the atmosphere. Biosphere - interface between the spheres water moves between hydrosphere, lithosphere and atmosphere by plant transpiration.

14 Hydrologic Cycle

15 Atmosphere Atmosphere is a dynamic mixture of gases that envelop the Earth. Two gases, nitrogen and oxygen make up most of the atmosphere by volume. Minor gases include have a significant impact on heat budget and the moisture across the Earth. Water vapor, Carbon dioxide Atmosphere has a layered structure as defined by vertical temperature changes.

16 Structure of the Earth Lithosphere Outer rigid part of earth includes the crust and upper part of the mantle. Act as a unit and respond similarly to mechanical deformation. 60 miles in thickness to 150 miles thick beneath continents.

17 Structure of the Earth Asthenosphere Lies beneath the lithosphere
Extends to a depth of about 400 miles. A small amount of liquid (from partial melting of the upper mantle) in upper 100 miles Detached from the underlying asthenosphere. Capable of flowing - convective.

18 Structure of the Earth Mesosphere - about 2500 km thick, solid rock, but still capable of flowing. Another name is Mantle. Outer Core km thick, Fe and Ni, liquid Inner core km radius, Fe and Ni, solid All of the above is known from the way seismic (earthquake waves) pass through the Earth

19 Quiz Questions Ques. 1: The earth formed: A. 455 million years ago.
B billion years ago C. 4,550 million years ago D billion years ago Ques. 2: Catastrophism could be use to explain: A. the formation of Grand Canyon. B. the evolution of the coastal area near Siccar Point, Scotland C. the presence of blue algae in stromatolites. D. the iridium-rich layer observed around the world at the K/T boundary.

20 Quiz Questions Ques. 3: The mesosphere is located between:
A. the solid inner core and the liquid outer core B. the liquid outer core and the asthenosphere C. the lithosphere and the asthenosphere D. the crust and the asthenosphere Ques. 4: To a close approximation, the term that best describes the Earth system is: A. an open system B. a closed system C. an isolated system D. an insulated system

21 Quiz Questions Ques. 5: The lithosphere is best described as: A. a stiff and rocky layer within the Moho region. B. a rigid layer found upward from the asthenosphere. C. a rigid layer found downward from the asthenosphere. D. a rigid and rocky layer capable of flowing Ques. 6: What are the Earth's "four spheres"? How do they interact? Ques. 7: What is the difference between catastrophism and gradualism or uniformitarianism? Can you cite an example of each?

22 Quiz Questions Ques. 8: What are the key physical properties of the inner core, outer core, mesosphere, asthenosphere, and lithosphere?

23 Citations

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