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Unformatted text preview: Homework #4, Geol 1020, Spring 2008 1. Which of the following is NOT geologic evidence for glaciation and/or climate change in the Pleistocene? A. oxygen isotopes in marine shells B. unsorted and unlayerd conglomerates (tills) C. pollen in lake sediments D. abundance of gasses in ice cores E. all of the above are evidence for glaciation and/or climate change 2. Fill in the blank with one word --- The earth's climate is an engine driven by __SOLAR____________ energy. 3. Why does the oxygen isotopic ratio of seawater change in a glacial period relative to a non-glacial period? A. the 16O isotope of oxygen selectively concentrates in the oceans when glacial ice sheets are growing B. the 18O isotope of oxygen selectively concentrates in the oceans when glacial ice sheets are growing C. the 18O isotope of oxygen selectively concentrates in ice when glacial ice sheets are growing C. the 18O isotope of oxygen selectively concentrates in ice when glacial ice sheets are melting 4. When geologists work with the isotopes of oxygen, they are working with ________ isotopes A. stable B. radioactive The figure below shows oxygen isotopic data collected from marine shells in a vertical record of late Pleistocene sediment (+ means an increase in 18O to 16O, - means a decrease in 18O to 16O). Note that the data is plotted with respect to depth, not time. Based on this plots, answer the questions below. 5. The sediments at points A and B were deposited in a _______________ period. A. Glacial B. Interglacial 6. Moving from older (A) to younger (E) sediments, the data between points A and E indicate ice sheets were: A. stable B. growing C. melting 7. The isotope proxy between points E and D indicate that climate was A. stable B. growing C. melting Mark the following as either True (T) or False (F) statements. 8. The last glacial period began about 120 thousands years ago and once it began, it was characterized by maximum glacial conditions throughout its history. ____FALSE, LOOK AT THE ISOTOPE CURVE______ (use the oxygen isotope plot for the last 1.9 my that we e shown for question 14 below). 9. Globally, glacial periods are marked by generally colder and drier continental climates. ___TRUE_______ 10. Glacial deposits like unsorted and unlayered conglomerates (tills) can be used to track the distribution of an ice sheet. ___TRUE______ 11. As glaciers grow larger, global sea level will rise. __FALSE (IT FALLS)________ ...
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- Spring '07