2 25 2010 Which principle of relative dating states that in an undeformed sequence of sedimentary rocks each layer is older than the one above and younger than the one below The present is the key to the past is a fundamental part of 1 2 3 4 In class activities catastrophism plutonism neptunism uniformitarianism Explanation Uniformitarianism holds that the physical chemical and biological principles that operate today also operated in the past Thus the present is the key to the past February 25 2010 Morning class results 94 1 2 3 4 6 1 1 3 4 4 Each sedimentary layer is older than the layer above Each sedimentary layer is younger than the layer above Each new layer of sediment is laid down nearly horizontally over older sediment Each new layer of sediment is laid down accordingly 2 1 2 3 4 74 simultaneously igneous before sedimentary sedimentary before igneous unknown 0 3 4 91 1 1 3 2 3 0 4 1 Ancient geologic processes as revealed in Paleozoic rock layers were 3 4 6 4 A scientific debate between Earth scientists Younger igneous plutonic rock above older sediments A continuous sequence of sedimentary layers A gap in an otherwise continuous time sequence of rock layers 91 2 9 3 3 0 4 1 2 3 4 radiometric dating relative dating superposition fossil assemblages through time 2 3 3 9 0 2 4 3 1 2 3 4 42 13 3 4 Fossil organisms follow one another in a definite irreversible time sequence 42 Rock cycling may dislodge and relocate fossils making their age difficult to determine A fossil is always older than the rock in which it is found All of the above 20 6 2 What is the principle of faunal succession 77 Explanation Presently the only way to obtain numerical dates is with radiometric dating 0 1 The numerical dates associated with events on the geologic time scale were determined by 85 predominantly volcanic in origin primarily glacial predominantly processes of erosion and sedimentation very similar to processes seen today 1 3 What is an unconformity 1 2 1 Explanation Remember The present is the key to the past 2 Explanation Unconformities represent a missing record of time like pages missing from a book 0 4 47 6 23 1 2 3 47 0 In a thick bed of sedimentary rocks we find an igneous dike According to the principle of cross cutting the order in which these rocks formed is What is the principle of original horizontality 2 0 Original horizontality Superposition Cross cutting Inclusion 3 3 0 4 1 2 3 4 1 2 25 2010 When comparing geologic time to a calendar year the time of the dinosaurs is in the 1 2 3 4 middle of October first half of December second half of December first half of February 1 2 3 4 36 EExplanation l ti Amazing as it may seem to many people dinosaurs are a recent phenomenon in Earth s long history The most important event during the Cambrian period was the Life forms in the Precambrian included trilobites brachiopods coelacanths cyanobacteria 1 2 63 3 4 24 21 18 27 10 43 emergence of the fishes ability of organisms to form an outer skeleton emergence of the trilobite ability of organisms to develop lungs 27 27 Explanation The evolutionary development of an outer skeleton increased survival rates 3 0 1 2 3 4 1 2 3 4 The fossil record spans about 3 5 billion years of Earth s 4 5 billion year age The most common fossils are those organisms that had hard parts like shells and bones The first fossils were simple anaerobic algal plants The Paleozoic era is credited with the emergence of life Explanation Life emerged in Precambrian time which precedes the Paleozoic era 3 4 The Mesozoic era is known as the age of the Which of the following is NOT true of the fossil record 1 2 1 2 3 4 dinosaurs synapsids fishes reptiles 45 2 3 4 During which era did pine and redwood trees appear 42 Explanation Dinosaurs are but one group of reptiles 1 1 2 3 4 Precambrian Mesozoic Paleozoic Cenozoic 39 32 25 10 4 3 1 2 3 4 1 2 3 4 2
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