Test Bank Solution Eosc 114- Impacts Already Passed

Test Bank Solution Eosc 114- Impacts Already Passed The Biosphere - Answers - a thin layer of life on Earth's surface - composed of ecosystems Stratigraphy - Answers study of layers of rock biostratigraphy - Answers part of stratigraphy that identifies the relative ages of rock layers using fossils Stratigraphy and Biostratigraphy - Answers - for studying the past - biosphere composed of individual pieces that have evolved through time - helps our understanding of the passage of time on Earth - the passage of time is recorded in rock layers Principle of Superstition - Answers in layered strata (sedimentary rocks, lava flows) "what's on top is the youngest" Principle of Original Horizontality - Answers if it's tilted or folded, it was originally flat Principle of Lateral Continuity - Answers if it's here it's probably over there too Principle of Cross-cutting Relationships - Answers if it cuts through, it's probably younger Uniformitarianism (Hutton, 1700) - Answers the same natural laws and processes that operate in the universe now have always operated in the universe in the past and apply everywhere in the universe Principle of Faunal Succession (Smith, 1799) - Answers Fossils succeed each other vertically in a specific, reliable order that can be identified over wide horizontal distances. - strata of like age can be dated and correlated by the fossils they contain Best Species for Biostratigraphy - Answers 1. Short fossil range = higher resolution 2. common 3. lived in environments where fossilization is likely to occur 4. present in many different environments Geological time scale - Answers - divides the Earth's history into time periods - many divisions based on extinction events Geological periods - Answers 1. Precambrian (4.5 Ga, 87% of earth's history) 2. Phanerozoic - (Paleozoic, 542 Ma) Cambrian, Ordovician, Devonian, Permian - (Mesozoic, 251 Ma) Triassic, Cretaceous - (Cenozoic, 65 Ma) Neogene Radiation of New Species - Answers - rapid diversification into new forms/ species after a mass extinction - mass extinction makes new resources available, creates new challenges, opens new environmental niches - occurs at the base of new geological time periods/ groups of periods What defines mass extinction? - Answers -at least 30% of species lost -broad range of ecosystems -short/sudden duration Mass Extinction Causes (biological) - Answers - Competition, predation pathogens, biogeology (mosses may have caused late Ordovician ice age and ensuing species extinction) Mass Extinction Causes (Physical) - Answers - Changes in continental configuration causes changes in climate, ocean cycles, sea level -Pangea super continentC - Atmospheric/ volcanism --> cold house/greenhouse Mass Extinction Causes (others) - Answers - Extraterrestrial - Combination of many factors Causes of Permo-triassic extinction - Answers 1. Continental configuration, super continent drop in diversity - less ecological niches = less diversity 2. sea level fall, less ocean ridge activity 3. Oceanic stagnation - anoxia (lack of O2) - Polar waters unable to sink, no ocean circulation 4. extraterrestrial bodes and other events 5. Climate change - Siberian traps (massive volcanic activity) = high CO2 in atmosphere - CO2 cause greenhouse warming, raises global temp by 5 degrees C Clathrate - Answers solid crystal structure containing methane from decay of organic material, common in deep ocean sediments - ocean warms > melts clathrate > release CH4 - adds 5 degrees C, now 10 degrees C warmer End of Cretaceous (65 mya) - Answers - at least 50% of species lost - on land nothing over 25kg survives - 80-90% of marine species lost Alverez Hypothesis - Answers - mass extinction at K/ Pg (65 mya) was caused by the impact of a large asteroid - enriched in iridium much higher than typical earth's crust Alverez support (Ferns) - Answers fern spores dominate sediment samples at K/Pg boundary - ferns first to colonize fire impacted landscape. - After impact, massive spike in % of fern spores in sediments Alverez support ( soot layers) - Answers Soot layers associated with the iridium layer, evidence of massive global fires Alverez support (tektites) - Answers Tektites, common at K/Pg and is evidence of a very large impact event - tektites are natural glass, produced by melting rocks during impact Alverez support (shocked quartz) - Answers -common at K/Pg - evidence of large impact - cross hatched lines = stress lines due to impact Alverez support (tsunami) - Answers Tsunami deposits found around much of the globe