Week 2 Notes
Week 2 Notes Geo 003
Popular in History in the Headlines of Life
Popular in Geology
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This 63 page Class Notes was uploaded by Yasmine Gohar on Thursday April 21, 2016. The Class Notes belongs to Geo 003 at University of California Riverside taught by Prof Mary in Spring 2016. Since its upload, it has received 7 views. For similar materials see History in the Headlines of Life in Geology at University of California Riverside.
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Date Created: 04/21/16
What do we need to know in order to understand the fossil record? What has a good chance of making it to the fossil record and what has a very slight chance? Depositional environments and what animals do for a living -where sediments are deposited, ultimately producing sedimentary rock rocks record environments -sandstones sediments- organic and inorganic sediments that get eroded- a certain percentage are transported to another environment one of the main tenents of geology- while life has evolved and changed the planet (as well as the bio of the planet) there are particular physical and chemical laws that do not change over time. The same processes that were created today are the same that produced them millions of years ago how do we go from sand to a sand stone? -depositional environments- environment where sediments are deposited rather than eroded -not all fossils are preserved where the organism lived different environments- we live on land- terrestrial environments are only about 30% of the earths surface WE DON’T HAVE AS GOOD A RECORD OF NON-MARINE ENVIRONMENTS AS WE DO MARINE (bias) Depositional environment- Swamps—imp because coal comes from ancient swamps -glacial deposits—often get eroded -rivers—much of our terrestrial deposits, a lot of our dinosaurs are found in rivers (BIG part of the terrestrial record) -Alluvial fans—where sediment comes down from a mountain (sometimes with water sometimes without) -lakes- Marine environments- MAJORITY OF DEPOSITIONAL ENVIRONMENTS 70% of the earths surface best fossil record Shallow marine environments: -beaches—worst fossil record -reefs- really good fossil record (fossils are literally building reefs) -intertidal- where beaches meet the land (not well preserved because intertidal are exposed and under the water, and are not depositional environments due to the rocks surrounding them) -Delta- river to ocean (dumping sediments of the river to the ocean) – good fossil record of deltas -Bulk of fossil record is in the continental shelf (bulk of ocean floor gets subducted) Benthic Organisms - Mostly invertebrates - Life on the see floor (clams) - Most of the fossil record - Mostly crabs, mussels, clams, oysters, starfish (all without backbones) Epifaunal organism- live on top of the sediment on top of the sea floor Infaunal- live in the sediment under the sea floor Sessile- fixed (corals) Vagrant- active (sea cucumbers) [holothorians] Suspension feeder- food that passes is eaten through some sort of suspension How we organize living and dead organisms -eukaryotes -species concept -describing a species -grouping species -cladistics 3 domains: eucarya, bacteria, archaea species: groups of individuals w genetic material from the same gene pool, amost always incompatible w that of another gene pool potentially interbreed to produce viable offspring --could be different ecosystems or just different ponds that are spaced Linnean system -a bunch of similar species are then grouped into a genus -just a way of organization -species, genus, family, order, class, phylum, kingdom -many species in a genus, but all are related when studying evolution- we are trying to reconstruct the pathway to find out the relationships and what came from where Cladistics: traces the evolutionary history or PHYLOGENY -we look at the way that we classify organisms (tracing phylogeny by which species appeared and how they are related) Clade- group of species descended from one ancestral species [groups of organisms that are closely related] Hierarchy-species belong to a clade which belongs to a bigger clade. Etc. --all mammals share characteristics, therefore they are more closely related Cadistics is based on the presence of shared derived characters (all mammals have fur and lactate) -advanced character/feature (not claws or jaws) -evolutionary novelty or homology (adaptations) HOMOPLASY-result of convergent evolution (when organism contain similar characters that were independently derived—no common ancestor) Ex. dolphins ichthyosaurs, sharks – all have fins and streamline bodies, however are not related with a common ancestor Intro to Geology: Introduction to Geology and Geologic Time • Plate tectonics and structure of the Earth • Rock Cycle – Sedimentary rocks • Steno’s laws • Relative and absolute dating Intro to Geology: Big Bang @ 13.7 Ga Earth Forms @ 4.5 Ga (start of toilet paper roll) Structure of the Earth Chemical Layers: Crust: Mostly silicates i.e. Silicon & Oxygen (Si, O). 2 types: - Continental - Oceanic Structure of the Earth Chemical Layers: Crust: Mostly silicates i.e. Silicon & Oxygen (Si, O). 2 types: - Continental - Oceanic Mantle: Silicates with Magnesium and Iron (Mg, Fe) Structure of the Earth Density Increases Chemical Layers: Crust: Mostly silicates i.e. Silicon & Oxygen (Si, O). 2 types: - Continental - Oceanic Mantle: Silicates with Magnesium and Iron (Mg, Fe) Core: Mostly Iron with some Nickel (Fe, Ni) Structure of the Earth Mechanical Layers: Lithosphere: *Rigid/Brittle* Crust & Upper Mantle Asthenosphere: Plastic/Ductile Upper Mantle Lithosphere (made up of plates) and Asthenosphere (slushy) • Plate Tectonics Radioactive Decayin the Core gives off heat è which cathe Lithospherearound on top of the Asthenosphere. Plate Tectonics Alfred Wegener (1880-1930) Theory of Continental Drift 1915 -Similar Rocks/Mountains on separate continents -Similar Fossils on Separate Continents -Tropical Fossils in arctic regions -Jigsaw Fit of Continents: “PANGEA ” Lacked a Mechanism Pangea: ~255 Ma NOT ACCEPTED UNTIL 1960 s ’ Plate Tectonics Plate Tectonics Tectonic Boundaries: 1) Divergent:Plates move Away from each other, e.g. Mid-Ocean Ridges or Rifts – East African Rift Valley Boundaries between plates • Divergent-spreadingcenters Plate Tectonics Tectonic Boundaries: 1) Divergent:Plates move Away from each other, e.g. Mid-Ocean Ridges or Rifts 2) Convergent:Plates Collide -Subduction Zones -Continent-Cont. Collision Plate Tectonics Subduction Zones: “WHERE OCEANIC CRUST IS DESTROYED” Dense Oceanic Crust subsides beneath Continental Crust. -Typically involves Arc Volcanism eg. Sierra Nevada, Cascades, Andes. etc. Plate Tectonics Continent-Continent Collisions: -Equal density continental crust collides and “stick” together **Neither is Destroyed** e.g. The Himalaya Boundaries between plates • Divergent-spreadingcenters • Convergent-subductionzones • Transform-sliding past one another – San Andreas Plate Tectonics Tectonic Boundaries: 1) Divergent:Plates move Away from each other, e.g. Mid-Ocean Ridges or Rifts 2) Convergent:Plates Collide -Subduction Zones -Cont-Cont Collision 3)Transform:Plates slide laterally along each other, e.g. San Andreas Plate Tectonics Convergent Boundaries: The oldest Oceanic crust on earth is ~180 Ma (Jurassic) The oldest Continental crust is 4.1 Ga (Archean) Why Might this Be??? Plate Tectonics Plate Tectonics – implications for Life! Plate Tectonics Introduction to Geology and Geologic Time • Plate tectonics and structure of the Earth • Rock Cycle – Sedimentary rocks • Steno’s laws • Relative and absolute dating Rock Types: 1) Igneous: Rock formed from cooled molten rock (magma or lava ) 2) Sedimentary: Rock formed from hardened sediment 3) Metamorphic:Rock that has been altered by heat, pressure, or chemical reactions The Rock Cycle Sedimentary Metamorphic Igneous Sedimentary Rocks: Typically, fossils are initially preserved in sedimentary rocks… Exceptions: lava flows, *ash beds* Lava Tree Monument, Hawaii Nebraska Beds, Sedimentary Rocks: Formation of Sedimentary Rocks: 1) Sediment is weathered and eroded from highlands, then transported and deposited in lowlands. (Clastic Rocks: Siliciclastics) 2) Sediment is precipitated from solution and deposited. This can be biogenic or abiogenic. (Chemical Rocks: Carbonates) Sedimentary Rocks: Formation of Sedimentary Rocks: 1) Siliciclastics: Sediment is weathered and eroded from highlands, then transported and deposited in lowlands. Sedimentary Rocks: Formation of Sedimentary Rocks: 2) Carbonates: Sediment is precipitated from solution and deposited. This can be biogenic or abiogenic. Sedimentary Rocks: Nicholas Steno (1638 -1686) -Fossil shark teeth; “Tongue Stoes -How can a solid be found in another solid? -Explanation: these rocks were one time “Fluid”… **Steno s Laws** -1667 Left the scientific community to become a Catholic Bishop “Father of Stratigraphy” Sedimentary Rocks: Steno s Laws: 1)Original Horizontality: All strata are deposited horizontally Sedimentary Rocks: Steno’s Laws: 1)Original Horizontality: All strata are deposited horizontally 2)Latteral Continui:y Strata are continuous laterally Sedimentary Rocks: Steno’s Laws: Youngest 1)Original Horizontality: All strata are deposited horizontally 2)Latteral Continuity: Strata are continuous laterally Oldest 3)Superposition: Oldest strata on the bottom (deposited first) and Youngest Strata on the top (deposited) last Steno s Laws • Superposition-oldeststrata at the bottom • Principle of original horizontality-strataare horizontal when laid down • Principle of Lateral Continuity-sediments form continuous layers Fry 2003 BBC website Introduction to Geology and Geologic Time • Plate tectonics and structure of the Earth • Rock Cycle – Sedimentary rocks • Steno’s laws • Relative and absolute dating Dating in the Rock Record • Relative-ordering • Absolute-measureof time Relative Dating • Fossils occur in distinct intervals • Correlation of assemblages • Subdivision of rocks based on fossils Correlation and Relative Age • Fossils • Marker beds Absolute Dating • Radioactive Decay: “Clocks in the Rocks” Absolute Dating • Isotope-anatom of an element with different # of neutrons (e.g. Carbon 14, 13, 12) • Certain isotopes are unstable (radioactive) Absolute Dating • Isotope-anatom of an element with different # of neutrons • Certain isotopes are unstable (radioactive) Parent Daughter (New element) (Unstable isotope) Halflife=time need for ½ of parent to decay Absolute Dating • Decay is predictable but spontaneous – think gambling, popcorn Absolute Dating RATE OF DECAY IS CONSTANT! Uranium 238 – 146 neutrons, 92 protons Lead 206 – 125 neutrons, 82 protons Absolute Dating • Known half lives-remain constant • Parent: Daughter ratio can tell us age Absolute Dates from.. • Most igneous • Very few sedimentary • Organic material
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