GEO-202 Evolution of Earth Spring 2024-Take Home Review Question Set 4 Your Name: Avery Brovelli Instructions
: provide concise answers to the questions listed below and have the completed question set ready for discussion Wednesday the 28
th
by 11 PM.
1.
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What are three categories of lithostratigraphic units that crustal rocks are grouped into? The three categories of lithostratigraphic units are groups, supergroups & formations.
2.
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What are unconformities? Unconformities are breaks within the geologic record which is caused by erosion and non-deposition. Unconformities lead to missing layers of rocks such are angular, disconformities and nonconformities. 3.
—Which of Stenos’ principles permits us to determine the relative age of layered sedimentary rocks?
The principle that permits us from determining this is “Steno’s Principle of Superposition.”
4.
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What are index fossils and why are they useful? Index fossils: organisms that are known to have existed during specific time periods. Useful: age, stratigraphic correlation, and relative dating. 5.
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What are key beds and why are they useful for dating and/or correlation of rocks succession in different regions. Key beds: sedimentary layers/they are easily recognizable. Useful for dating: distinctive, stratigraphic correlation, time markers and are successions in different regions. 5.
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What are four types of radioactive decay reactions that unstable isotopes of chemical elements undergo when they decay to form stable isotopes of another element? 1. alpha, 2. gamma and 3. beta decay. 4. Electron capture. 7.
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Outline Steno’s three Stratigraphic Principles. These principles are the fundamental concepts for geologists to help understand relative ages of rock layers. The principle includes Superposition (oldest to younger layers), Horizontality (horizontal layers) and Lateral Continuity (extending till thinned out) 8.
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How can radiometric ages of igneous or metamorphic rocks be re-set? It can be re-set by a process known as isotopic resetting which can occur due to many geological events. One event example could be metamorphism. 9.
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Why is Bishop Ussher well known in the geological community? He is well known for his work related to attempting to determine the age of the Earth. The work is more based on biblical chronology. 10.
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Why is fossil succession useful for relative age dating of ancient sedimentary rocks? It allows geologist to establish a chronological order of rock layers. As finding out index fossils.
