Week Seven Notes-Geology G-104
Week Seven Notes-Geology G-104 GEOL-104 20584
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This 3 page Class Notes was uploaded by Ashley Hughes on Friday February 27, 2015. The Class Notes belongs to GEOL-104 20584 at Indiana University taught by Laura Wasylenki in Spring2015. Since its upload, it has received 103 views. For similar materials see Evolution of the Earth in Geology at Indiana University.
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Date Created: 02/27/15
22415 G104 0 Can you put the letters in the correct order using Steno s principles Oldest Sedimentary J K F H Tilting of J K F H Erosionunconformity B G Igneous intrusive Erosion E I Erosion C A L duck Limestone Marine shelf Shale Shallow Sea with mud Sandstone Beach o If we look at many regions we can reconstruct what North America looked like at some point in the distant past 0 FOSSILS add another dimension to our quest 0 How dinosaurs and other organisms become fossils Chart on PowerPoint on Oncourse O O O O Petrified wood Mineralized plant tissue Coprolite feces Trace fossils burrows o In recent years we ve learned to detect fossils that are chemical molecules organisms made rather than physical remains 0 Find molecule in ancient rocks assume the bacteria today was around then present is key to past 0 Will Smith made first map in Great Britain 0 O O Smith observed and recorded the fossils in the sedimentary rock he mapped He drew this cross section to show the order of the rock formations Each species of fossil appears over a certain interval and it s never seen below or above that interval and never appears out of order relative to other fossils Smith realized that the fossils in a rock correlate with its age I He figured out he could map a time scale based on the fossils found in the rocks Smith observed that there is a family tree of fossilized life just as Linnaeus was figuring out the presentday tree of life See PowerPoint on Oncourse Smith and other geologists began to define a fossilbased time scale The major boundaries in the time scale are major mass extinctions and the minor boundaries are minor mass extinctions 22615 0 19th century geologists figured out they could use Steno s laws plus fossil succession to put all the rocks they saw in order by age 0 Index fossil gives tight constraint on when that rock formed 0 Fossilizes well 0 Widespread o Shortest life tight age constraint 0 Uniformity possibly eroded other areas from other times away Triassic 39 Ordovician o The present in not always the key to the past 0 Not same organisms today than in the past 0 Usually the present is the key to the past but here the ancient rocks teach us about modern processes 0 Past is key to present Harmful Variation lower chance of surviving to reproduce variation does not become common in population Neutral Variation no consequence Beneficial Variation higher chance of surviving to reproduce variation becomes common in population DJ E u i i 8 b O Q u i E O 395 CG u i E gt E O 39U Q CG Q4 0 Over a long time this can lead to changes in families species genera etc 0 Some species evolve fast enough to notice if you are careful to measure 20 years 0 DNA blood also changes genes 0 Evolution now a theory with a mechanism 0 Understood better than the law of gravity
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