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Unformatted text preview: Name: Geology 101 Exam 2 Monday, October 27, 2008 This exam consists of 40 multiple-choice questions. Only one answer of the four given is correct. Blacken the appropriate circle on your computer form to indicate your selection. Erase completely any stray marks on the form. NOTE : There are only four responses on your exam and Fve on the computer form. Never blacken the Ffth circle on the computer form. 1. Human beings (Homo Sapiens) evolved during which geologic era? a. Cenozoic b. Mesozoic c. Paleozoic d. Precambrian 2. An unconformity is _______. a. a layer of sedimentary rock b. an erosional gap in the geologic record c. a layer of rock with very unusual fossils d. a period of deposition 3. Which of the following sequences is written correctly from oldest to youngest? a. Cenozoic, Paleozoic, Mesozoic b. Mesozoic, Cenozoic, Paleozoic c. Paleozoic, Mesozoic, Cenozoic d. none of these 4. Lord Kelvin's estimate for the age of the earth: a. was too high because he did not know about convection in the mantle, which increases the rate at which the earth cools b. was too low because he did not know that the decay of radioactive elements in the earth produces heat c. was too high because he overestimated the initial temperature of the earth d. was too low because he assumed a thermal conductivity for rock that was too high 5. A rock formed with 2,000 atoms of a radioactive parent element, but contains only 500 radioactive parent atoms today. If the half-life for the radioactive element is one million years, how old is the rock? a. 250,000 years old b. 500,000 years old c. 1,000,000 years old d. 2,000,000 years old 6. A grain of feldspar crystallized from a rhyolitic magma and incorporated 8000 atoms of a radioactive element with a half-life of 20 million years. At a later time, this rock underwent regional metamorphism that caused all of the daughter atoms produced by decay of the parent to be driven out of the crystal. If the mineral originally crystallized 100 million years ago and the metamorphic event occurred 60 million years ago, how many daughter atoms are present in the crystal today? a. 7750 b. 1750 c. 2000 d. 6000 7. Dinosaurs became extinct at the end of the _______Era. a. Cenozoic b. Mesozoic c. Paleozoic d. Precambrian 8. During metamorphism, the ______ of a rock may change. a. mineralogy b. texture c. chemical composition d. mineralogy, texture, and chemical composition 9. The principle of superposition states that _______....
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This document was uploaded on 10/28/2011 for the course GEOL 101 at UNC.
- Fall '07