Week 3 notes
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This 3 page Class Notes was uploaded by Vanessa Notetaker on Wednesday January 27, 2016. The Class Notes belongs to at Florida State University taught by David Houle in Winter 2016. Since its upload, it has received 16 views.
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Date Created: 01/27/16
WEEK 3 VIDEO NOTES Creationist – doubts in evolution Australopithecus afarensis – “Lucy” scientific name. Controversial fossil Click on cited by ____ on Google to find a long list of papers supporting your evolutionary claim. Or you can use “web of science” Good paper strategy: 1. Do an initial search 2. Quickly scan for a relevant paper 3. Do a citation search on that paper Dating the past Geology – study of earth history Paleontology – study of fossils 2 ways of telling time Looking at a clock Radiometric dating using isotopes in rocks Relative dating – looking at the context in which you find a rock or fossil and then being able to say it’s younger than something or older than something. Elements of geology Charles Lyal – published 1838 Look at rocks and name them (sedimentary rocks – settled out of water and compressed to form a rock) Volcanic rocks (igneous rocks) – result of volcanic activity Metamorphic rock – igneous or sedimentary in origin and buried deep and then changed into a different rock Thought the earth was millions of years old (Darwin thought this as well, read it on a ship) Uniformitarianism – the events we see happening on earth today are all processes that went on in the past as well Geological processes Sedimentary rocks – made of sediments that settle out of water. Most of the rock is from ocean. Rocks form in layers depending on the course of the river Principle of superposition – older rocks on the bottom, younger rocks on the top. The reason for this is gravity Lava flows over sedimentary rock Clues in the surfaces that give way of which side was up earlier on when rocks are eroded Pointed crests up Rounded troughs – down Erosion exposes the older rocks Unconformity – gap where the rocks are older at bottom younger at top but don’t have all the ages in between 550 million years ago first fossils Orogeny – mountain building. Continental drift, one plate goes up and one goes down in the lithosphere When plates collide, there is a break where weird things happen Intrusion – igneous rocks can intrude into overlying layers. Younger rock intrudes into older rock Principle if crosscutting relationships: intrusions are younger than rocks they intrude into Inclusion – pieces of older rock in younger rock Hot volcanic rock will change the characteristics of the rock it comes in contact to Relative dating Fossils Principle of faunal succession – characteristic creatures live at the time particular rocks were deposited We usually use marine organisms The first use of fossils – William Smith, map published 1815, The Map That Changed the World, built canal and became acquainted with rocks. Two different sediments would have been laid down at the same time due to their biological properties and fossil presence. Faunal succession – finding the same fossil organisms in the same vertical sequence in different places suggest that the rocks were laid down at the same time. Index fossils – common fossils found in the same sediment worldwide. This helps in dating the fossil’s relative age. Summary of relative dating 1. Superposition. Younger rocks are generally laid down on top of older 2. Crosscutting relationships. Intrusions are younger than the rocks into which the intrude 3. Exceptions (unconformities) can be explained by a. Erosion b. Faulting and folding can move older rocks over younger 4. Faunal succession. Rocks with similar fossils were laid down around the same time Radiometric dating Equal to reading a clock Isotopes are unstable and break off over time. They give of radioactivity over time Unstable isotope breaks down, loses molecular weight, and changes element Exponential decay ½, ¼, 1/8, 1/16 Most useful isotopic dating – C14 (useful for dating organic matter that is associated with human remains), N14 Halflives of unstable isotopes are all different Age of earth is 4.5 billion years old Grey distance on radiometric dating graph is accumulating “daughter” isotopes Blue under curve is the surviving “parent” isotopes Assembling the evidence
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