Week 1 Notes (1/8-1/15)
Week 1 Notes (1/8-1/15) GEOL105
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This 11 page Class Notes was uploaded by Maddibrooks on Friday January 8, 2016. The Class Notes belongs to GEOL105 at College of Charleston taught by Egerton in Spring 2016. Since its upload, it has received 116 views. For similar materials see Earth History in Geology at College of Charleston.
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Date Created: 01/08/16
Maddi Brooks Notes 1/8 History of Paleontology and Intro To the Fossil Record I. Chinese Dragons i. Tempting to link tales of dragons in China with the tale of dinosaurs, but there is no real proof of dragons II. Greeks and Fossils a. Hippocrates (460-357 BC) i. Collected Fossils b. Herodotus (484-425 BC) i. Observed fossil shells in Egypt ii. Used as evidence that Egypt was once underwater c. Aristotle (384-322 BC) st i. 1 to propose the idea of Natural Selection d. Leonardo Da Vinci (1452-1519) i. Fossil shells being found in mountains, so must have been ancient sea there e. Conrad Gesner (1516-1565) i. Came up with the term “fossil” 1. Fossil means “something dug up” 2. Term liberally applied to organic and inorganic items dug up ii. Considered to have began modern zoology f. Robert Plot (1640-1696) i. Considered fossils as “formed stones” and resembled animals by coincidence ii. Correctly identified (Megalosaurus) femur bone of large animal g. James Hutton (1726-1797) i. Founder of modern geology ii. Whewells theory of Uniformitarianism III. Uniformitarianism a. “The present is the key to the past” b. First principle of geology c. Major emphasis on immensely long time periods, cyclical process of erosion, deposition, sedimentation, and volcanic upthrust d. Suggests that Earth's geologic processes acted in the same manner and intensity in the past as they do in the present i. Such uniformity is sufficient to account for all geologic change IV. Examples of Uniformitarianism can be found on the PowerPoints uploaded on OAKS Maddi Brooks Notes 1/11 I. Basic Stratigraphy a. Beds: distinct lithological layers b. Bedding planes: the surface c. Cross bedding: bedding at an angle II. Nicholas Steno a. Also know as Niels Stenson b. First person to try and define a fossil c. Father of stratigraphy d. Laws of Stratigraphy i. Law of Superposition 1. In case of strata, layers on top of a set of strata conform to the shape of lower layers 2. Those on bottom are older than those on top ii. Law of Original Horizontality 1. Layers of sedimentary rock are originally deposited flat and “bend” over time iii. Law of Cross-cutting Relationships 1. Rock layers A & B must be older than the intrusion C that disturbs them (refer to image of his Laws) iv. Principle of Lateral Continuity 1. Same rocks beds, even in gapping spaces 2. Look at other image provided of this law III. Unconformities a. Unconformity: An erosional or non-depositional surface separating beds i. Breaks in deposition=missing time b. Types of unconformities i. Disconformity 1. Erosional or non-depositional break in parallel sedimentary rocks ii. Angular conformity 1. Horizontal strata are deposited on tilted sedimentary rocks iii. Nonconformity 1. A bedding layer between underlying metamorphic or igneous rocks and the overlying sedimentary rocks IV. Fossils and the Fossil Record a. Tongue Stones i. Thought to protect against deliberate poisoning 1. Would be worn around your neck or somewhere on your body 2. Shark tooth ii. Steno argued the tongue stones looked identical to shark teeth and had to have come from an organic being 1. Argued fossils could be altered in chemical composition without changing their form Maddi Brooks Notes 1/13 I. Fossils i. Tangible evidence of organisms in the past b. Body Fossils i. May have replacement by pyrite, silica, phosphate, carbonate, etc. ii. Mummy iii. Compression iv. Coral builds carbonate exoskeleton from Aragonite and it becomes calcite over time c. Natural Cast i. Actual shell gone, but a cast/model made of the organism d. Chemical fossil i. Chemical composition still there ii. High-powered x-ray shot at fossils to reveal chemical composition designated by different colors e. Examples of each fossil type can be found on the OAKS PowerPoint II. Taphonomy a. From the moment something dies to the moment it’s found and the processes that happen in between b. Everything from decomposition, where it’s decomposing, the conditions after it’s buried, etc. c. “The science of the laws of embedding” and “a study of the transition of organic remains from the biosphere into the lithosphere” d. The processes of fossilization lead to selective bias within the fossil record e. Taphonomy seeks to distinguish primary paleobiology v. taphonomic artifact f. Not everything makes it into the fossil record i. Example: Just because we don’t find millions of dragonflies in the cretaceous period, doesn’t mean they didn’t exist. It just means they weren’t preserved g. Animals that live in cooler climates are more likely to be preserved, because in hot and humid climates, decay happens really fast h. Taphonomic Process shown in image III. Decomposition a. Tightly linked to how an organism is preserved (affects the taphonomy) b. Even if we have three triceratops in the same horizon, we can’t say they lived at the same time and interacted c. Shells are the most likely thing to be entered into the fossil record, because they are small, get buried quickly, and are in contusive environments d. Things that live in the ocean with a hard part are more likely to enter the fossil record than anything on land e. Mountain goats not likely to get in the fossil record, because the mountain is an erosional environment i. Even if it got buried, it would likely be eroded into sediment over time f. Fast vs. Slow Burial of Dinosaur IV. Information Loss and Taphonomic Bias a. Taphonomic Bias i. Geologic time 1. The further you go back in time, the least likely it is to find fossils ii. Burial Time iii. Type of ‘body’ 1. Hard or soft body iv. Burial location 1. Ideally, need location with high deposition, not high erosion a. Like sides of a river, seafloor, riverbed (deposition) v. Bias collection vi. Best record=marine shelled organisms vii. Worse=organisms with no hard part Maddi Brooks Notes 1/15 Climate Change I. Climate Change a. Weather=short timespan i. Seasonal b. Climate=long timespan i. About 30 years II. Causes of climate change a. Atmospheric gas composition i. Oxygen, Carbon Dioxide, Nitrogen, Argon, and water vapor ii. How the whole Greenhouse Effect works iii. Greenhouse gases increase, temperature increases 1. Gases prevent infrared radiation from going back out into space 2. Less plants=less carbon dioxide being pulled out of the air 3. Burning coal (carbon dioxide that was buried) and releasing it back into the atmosphere iv. Greenhouse gases decrease, temperatures decrease 1. Able to lose infrared radiation and release it into space v. Primary greenhouse gases 1. Carbon Dioxide 2. Methane 3. Water vapor vi. Geological and Biological changes affect greenhouse gases 1. Ex: Volcanism (release CO2), Siberian traps, respiration of plants (take in CO2), vertebrates (release CO2), bacterial respiration (release CH4), anoxic decomposition (release CH4) a. CH4=methane b. Anoxic=without oxygen vii. Greenhouse gases are important 1. Without them, Earth would be -18degrees C 2. Todays temperature approx. 15degrees C b. Albedo i. Ability to reflect sunlight 1. Black=Reflects 0%, Absorbs 100% (Low albedo) 2. Gray=Reflects 50%, Absorbs 50% 3. White=Reflects 100%, Absorbs 0% (High albedo) 4. ii. Affects Albedo 1. Snow, clouds, rocks, vegetation 2. 85%-90% reflected by snow 3. 10% reflected by ocean 4. 20% reflected by vegetation and dark soil c. Plate tectonics i. Subduction zones and seafloor spreading 1. Tend to have volcanoes 2. Increase volcanism=increase CO2 ii. Continental location 1. All of the continents close together with affect ocean currents vs. how it is now 2. When close together, Antarctica and places in Southern hemisphere were warm, because no current was around them a. Dinosaurs lived here year-round b. Like New England weather 3. Current near Antarctica now causes it to be cooler, because no warm waters reach it iii. Mountain building 1. Mountain building=erosion of rocks a. Rocks break down i. Surface area increases 1. Increase in chemical weather a. Increase in taking CO2 out of atmosphere 2. Rain Shadow Effect a. A rain shadow is a patch of land that has been forced to become a desert because mountain ranges blocked all plant- growing, rainy weather. On one side of the mountain, wet weather systems drop rain and snow. On the other side of the mountain—the rain shadow side—all that precipitation is blocked. b. If wind is approaching from the west, the rain shadow is on the east. If the wind is approaching from the east, the rain shadow is on the west. i. Rain shadow side is opposite of the side with wind c. A rain shadow forms when moist winds head towards a set of mountains and get forced upwards by them. This moist air often comes from the sea or from another large body of water. i. Because where there is water, that water can evaporate. The more water that evaporates, the more moist the air becomes. d. When an air mass moves from a low elevation to a high elevation, it expands and cools. e. The cool air cannot hold moisture as well as warm air, so the cool air forms clouds, which drop rain and snow, as it rises up a mountain. f. After the air mass crosses over the peak of the mountain and starts down the other side, the air warms up and the clouds begin to disappear. That means there is less rainfall. d. Not independent factors i. Atmospheric gas composition, Albedo, and plate tectonics ii. Ex: Two plates converge and build mountains (India + Asia = Himalayas) 1. This creates: a. Rain shadow b. Changes in atmospheric circulation pattern c. Increase weathering of rock = chemical and physical weathering pulls CO2 from atmosphere and sequesters it to sediments d. Higher mountains = increase in snow = higher Albedo
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