12-1 & 12-3 Notes
12-1 & 12-3 Notes GEOL 1200 - 003
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GEOL 1200 - 003
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This 6 page Class Notes was uploaded by Keely Haggar on Sunday December 6, 2015. The Class Notes belongs to GEOL 1200 - 003 at University of North Carolina - Charlotte taught by Jake Armour in Summer 2015. Since its upload, it has received 20 views. For similar materials see Physical Geology (no lab) in Geology at University of North Carolina - Charlotte.
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Date Created: 12/06/15
Geology 1200 121 Chapter 1819 Geologic Time amp Intro to Earth History Final Exam is majority of these Chapters gt Relative Age Dating 0 Ex Stripes on a sedimentary rock the lower stripers are older gt Absolute Age Dating 0 Ex Carbon 14 Dendritic drainage patterns on mars Natural Stream Terraces in Khazakstan gt Tectonic uplift gt Rivers are actively evolving in response to uplift gt Floodplains The area adjacent to an active stream 0 Typically active when they re connected to the stream 0 Smooth out floodplain and make it pretty wide gt Terrace Abandoned floodplains old floodplains 0 Down cutting rivers creates this 0 River gets steeper by terraces that were once part of the old flood plain o Keeps going and now you have two terraces 0 Top terrace is the oldest 0 Lowest is the youngest 0 River responds to what is happening upstream Terrace surfaces are important for agriculture and development o In a response to mountain uplift rivers will down cut not all at once and create many terraces 0 Use C14 to date up the terrace we find out by measuring that 50 meters away where we took our sample 0 1000 ybp uplift rate 50 m1000 years 005 myr 5 cmyr Tree Dating 0 Thick growth ring forms in the majority of the year 0 Thin ring forms when the tree is dormant in the fall 0 Climatic conditions effect the condition of the growth rate Dendrochronology Treering dating gt Bristlecone Pine CA 0 Trees can live up to 4000 years 0 Current chronology goes back to 7000 years I You have to get a microscope out to see the rings they re tiny gt You can establish Chronology by comparing it things around the tree to that tree o Anasazi Ruins I Abandoned in AD 1150 0 People were trying to figure out when they were making these places they found as ruins 0 When were the Anasazi populating the US 0 The Anasazi used wood roof beams which had tree rings I Looking for drought rings they looked for a nearby dead tree experiencing the same events 0 Finding a younger tree experiencing the same events late in its life and an old tree experiencing the same events early in its life gt All time keepers have these three characteristics 0 A closed system 0 Changes that are observable at a constant rate Geologic Time Chapter 18 gt Carbon 14 With these Marble Rocks in order to date Stonehenge with a closed system gt Fires made in the middle of Stonehenge dating the wood or charcoal with Carbon 14 Relative Age of Stonehenge gt The age of a geologic feature in relation of other geologic features 0 Stonehenge is younger than the rocks that make up Stonehenge Absolute Age gt Numerical age The age of a geologic feature in years Relative Age pic gt This environment contains sandstone and limestone in the same environment which you aren t supposed to see gt Principle of Superposition o Developed by Nicolaus Steno o In an undeformed sequence of sedimentary rocks or layered igneous rock the oldest rocks are on the bottom 0 Layer cake 0 We didn t see it being made but we know I Layer ice layer ice layer ice 0 Grand Canyon is an example of this gt Later on might get eroded or titled by tectonic forces gt Principle of Original Horizontality 0 When deposited sediments are horizontal gt Principle of Original Continuity 0 When deposited sediments gt Principle of CrossCutting Relationships 0 Not all rocks are sedimentary o If one feature cuts across another the feature being cut is older The feature doing the cutting is younger gt Cross Cutting Relationships TWO PICTURES o Volcano erupting cross cutting multiple layers light gray brick pattern Limestone dark gray dashed pattern Shale speckled yellow pattern SandstoneSand o Limestone Shallow Marine Equatorial Conditions Shale Deep water 0 Sandstone Beach I Transgression Sea level rises Moving the shore line landward I Regression Sea level drops 0 gt Later 0 A lot of the sandstone was removed and so was the volcano I We lose the contact between the Dike and the Sandstone I Transgression and regression you can still tell it occurred but you lose the other geologic time relationships gt Principle of Inclusions o Inclusions are older than the rock they are included in I Ex Fossils I Ex Ruby trapped in diamond Ruby formed first and the conditions changed which allowed for the Diamond to grow and form around it When did the folding happen PIC a Before the deposition of 4 b After the intrusion of the basalt dike c Before the fault offset d Cannotsay Steps 1 Find the oldest thing in the case Limestone 2 By process of elimination The fault line is perfectly straight if that happened before the folding that would be bent too gt WAIT This picture violates superposition because layer 8 is out of order 0 It is an intrusive igneous rock is not sedimentary has pieces of4 and 5 inclusions o Inclusions are always older than what they are inside of gt The Granite Pluton has chunks of 5 in it sandstone so it has to be younger than 5 Deep Time Cont 1003 Chapter 18 Geologic Time How many unconformities are pictured in this cross section pic Curvy lines on a diagram Erosional surface gt typically associated with nonconformity gt look for two rocks next to each other with a curvy line and they are different types ie Metamorphic next to igneous gt In this example specifically Granite right next to sandstone o Volcanic Ash Igneous gt You know erosion occurred because of the strange relationship between rocks Big gaps in time between the different rock units stacked on each other pic Where is the angular unconformity gt Where the rock hammer is just above the head gt You cannot get vertical sedimentary rocks so these here have been moved deformation 0 You cannot deposit two sedimentary rocks at two different angles without deformation Angular Unconformity gt Sedimentary RX 0 On top of tilted and eroded I Sedimentary Rx diagram gt Convergent High grade metamorphic rock called schist Nonconformity gt Sedimentary RX 0 On top of eroded gt Igneous or Metamorphic Rx How many years old are the fossil bones in the Cretaceous sandstone a 50 MA b 80 MA c 125 MA d 5080 MA e 80125 MA ans e 80125 MA Once bones are fossilized they don t have carbon in them so carbon 14 is not a valid dating method gt If you have bones that are still in tact you know that the event causing the sediment to form caused the death of these animals Therefore they re the same age gt You can ONLY get an absolute age from an Igneous rock Jurassic Period 150 MYA TRex Triassic Principle of Fossil Succession gt William Smith 0 A fossil species is found in a definite range of layers I Not above or below The top of where a fossil is found extinction Use to determine the relative ages Index Fossil A short lived organismfossil used as reference Clam shells are a common fossil not a good index fossil I Something that is still alive and hasn t changed much is not a good index fossil OOOO Determining the ages of rocks using index fossils gt Using rocks and processes to understand time Which of these fossils is the best index fossil DQIPP39P Through this geologic outcrop we are seeing evolutions through the ocean Correlation Matching the rocks from one location to another gt Lithologic Correlation Correlating rocks based on a similar rock type 0 Le Pangea is based off of correlation based off of similar rock type gt Fossil Correlation Correlating rocks gt Effective correlation Looking at the Grand Canyon you can see the stripes across relating from one top to the other gt Correlation is an important interpretation for making geologic maps gt Time Correlation o Create a chronology that has overlaps then you go from youngest to oldest event giving them names 0 This distinguishes the Jurassic from the Triassic to the cretaceous 0 Geologic Time Scale No numbers just descriptions of what was found in the fossil record 0 Paleozoic Color coded blue Marine organism fossils o Mesozoic Marine organisms turned into amphibians o Cenozoic Amphibians 9 reptiles What atomic particle defines an element a Electrons b Protons c Neutrons d Muons