Testing Hypotheses & Understanding Geological Processes: Plate Tectonics & Earth's History, Study notes of Geology

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Expanding Earth Hypothesis : video clip shown in class on this by Neal Adams in 2005 -how to test if his hypothesis is accurate? -do continents fit together like suggested? -stated there was no subduction, so if we find subduction it will disprove hypothesis -seafloor looks smooth in the video picturesso how do we explain mid-ocean ridges? -Australia has to move to China to close the Pacific according to the video which doesn’t work out after being researched Theory of Plate Tectonics: Seafloor Spreading: must look for formation of new ocean crust and old crust spreading apart to support this hypothesis Evidence to back this up:

1. Median Rift Valley
2. Magnetic Stripes
3. Earthquake Activity
4. Lava flows—new basaltic material is created
5. Hydrothermal Activity—it is hot at the crest of the mid-ocean ridge; cold sea water gets pulled in and turns hot and is then pulled back up, cooling the Earth Seafloor Vents: organisms live around where this hot water is pulled back up Subduction Zone: Evidence to back this up:
6. Oceanic Trenches
7. Island arcs—two ocean plates; one plate is subducted forming this and volcanic arcs
8. Continental Volcanic Arcs—ocean plate subducts under the continental plate
9. Earthquakes—occur typically in zones slanted in towards the continent (picture drawn in class showed this occurring at a trench below a volcano)
10. Seismic-imaging of Down-Moving-Slabs Measuring Plate Motion: -Satellite Global Position System -tells where you are, the time it is, and if you remain in one position is can tell you what direction you’re moving (the plate under you) and how fast Driving forces of Plate Tectonics: -Mantle Convection: Earth loses heat as a result of hot material coming up and moving back down, forcing Earth to lose heat -We don’t know how deep cells exist -This is similar to a pot of water on a stove that is heated enough to where the water is hot on the bottom and cool on top; the water turns to make the cool part come back down which slightly cools all the water in the pot. Climate and Climate Change:

• Climate =weather over long periods of time -Focusing on temperature (warm vs. cool) and precipitation (wet vs. dry) -South Louisiana has a warm and wet climate
• Heat Budget : where does the warm come from? why does it cool?

-Greenhouse: constructed to trap heat -Source of heat (sun)some of the light is reflected back into space, some passes through the glass and interacts with the soil, and some gets converted into heat -The presence of glass is important because it traps heat. -With Earth, the atmosphere acts as the glass and turns light to heat (greenhouse gases) -Also with Earth, the sunlight is reflected back into space and if there are clouds or ice present they too will reflect light back into space. -Circulation of Atmosphere and Ocean : transports heat and moisture from one part of Earth to another which controls the distribution of life forms on Earth Greenhouse Gases:

- Most abundant gases in the atmosphere are nitrogen, oxygen, and argon which aren’t greenhouse gases. - Carbon dioxide (CO2), Methane (CH4), and Water Vapor (H2O) are all greenhouse gases. - Volcanic activity can create carbon dioxide and methane. Power Point Portion of Notes: Permian (260MY) to Today: The breakup of Pangeathese notes will be posted on Moodle, but we won’t be responsible for them. Albedo is the reflection of sunlight back into space. Oceans and forests converts light into heat which radiates into the atmosphere. Greenhouse gases act as insulters. Known as the Greenhouse Effect. -Clouds help contribute to it. If hit directly, the sunlight goes back into space. -Greenhouse gases contribute too: water vapor is the most significant. -Carbon dioxide and methane are the other two greenhouse gases. If we didn’t have any greenhouse gases in the atmosphere our surface temperature on Earth would be 31 degrees Celsius cooler, about 60 degrees Fahrenheit cooler. Today our average temperature is 25 degrees Celsius. So it would be -14 degrees Celsius without greenhouse gases. Water freezes at 0 degrees Celsius. We would have a frozen planet for the most part—salt in the oceans might keep some parts liquid. Variations in Heat Budget of Earth : Variations in:

1. Solar Luminosity—brighter the sun, the more sunlight we can see, the more heat energy generated --the solar luminosity was 15% lower in Precambrian
2. Orbital Elements a. circular orbit vs. elliptical =does both --circular—gets same amount of sunlight throughout the year --elliptical—gets certain amount of sunlight at two times of the year and another the other two times of the year b_. tilt of axis_ c. precession —Earth spins like a top
3. Greenhouse Gases—water vapor

-When it’s water we get more water vapor into the atmosphere which absorbs more heat which gets more water vapor—feedback effect -Carbon dioxide—removed through plants; volcanic eruptions create carbon dioxide -Methane—produced by micro-bacteria

4. Albedo of the Earth If you have thick ice sheets, the albedo increases and reflects more sunlight into space, cooling Earth and vice versa. Creates a feedback effect. Climate Box: -Chris Scotese : -Role of Atmosphere and Ocean Circulation on Climate: -Looking at the North Pole to the Equator and then dividing that into three sections: --0-30 degrees: gets heated up on the equator and air rises up because less dense and then cools off at 30 degrees and circulates back down; the equator is also wet, so rain occurs (think jungle); makes a counterclockwise movement --30-60 degrees: air moves straight up and then comes down; therefore, the air is dry and warm at the 30 degrees (think desert); makes a clockwise movement --60-90 degrees: cool, wet climatic zones; air has lost all moisture, gets cold, so cool and dry at 90 degrees; makes a counterclockwise movement **So at 0 degrees it is warm and wet (jungles and rainforests), at 30 degrees it is warm and dry (deserts), at 60 degrees it is cool and wet (forests and grasslands), and then at 90 degrees it is cool and dry (ice) -Temperate climates: --Today we have a strong climate gradient, hot at the equator and cold at the North and South poles. --Triassic period: weak climate gradient, not a huge difference going from the equator to the poles. It was pretty much arid and there was a tropical belt here and there. Otherwise, it was pretty much warm. Coriolis Effect : -Between 0-30 degrees there is a wind direction on the surface to the Earth that flows East to West, driving ocean water that way. From 30-60 degrees, the wind direction goes from West to East. From 60-90 degrees, it goes again from East to West. -Above the equator the ocean current moves clockwise, below the equator the ocean current moves counterclockwise and then there is another ocean current that circles Antarctica. -Climate along the Asia coast is warmer than the waters around North America. Also, the climate along Australia is warmer than the climate of South America due to the circulation of ocean current. -If continental plates move, the climate can change. Effect of Mountain Building: -Air above water is warm and moist which is forced to rise up over a mountain range. The air cools off and water vapor creates rain. The air is then forced back down and is now dry and warm (closer to the surface). So there might be a forest over a mountain range and then a desert on the other side of the range due to the dry, warm climate.

Climate Proxies: -Cool, Dry Climate: Glaciers makes till and tillite. Drop Stones: layered lake sediment (fine sediment) has a pebble in it (ice probably moved out onto the lake and then dropped into the lake creating this pebble) -Warm, Dry Climate: Evaporites formed in oceanic and continental settings. Calcium Carbonate cements in this climate which is called Calcrete. -Wet, Warm Climates: Coal deposits need a lot of rain to keep plants growing. Bauxite is aluminum oxide. Laterite is red soils that leech out everything but iron. -Cool, Wet Climates: Coal and Tillite are formed. Power Point Portion of Notes: Heat Budget:

1. Solar luminosity
2. Orbital elements
3. Greenhouse gases
4. Albedo -clouds, ice -volcanic activity Water vapor is the most significant greenhouse gas. Albedo: the amount of light reflected back into space; the lowest albedo is the Mediterranean; highest albedo is Arctic ice, snow What effect did the eruption of Krakatoa in 1883 have on the climate of the Earth? -It lowered global temperatures for several years. What famous painting was inspired by the eruption of Krakatoa? -Edvard Munch “The Scream” 1893 Circulation of the atmosphere:
5. Convection occurs
6. Coriolis effect: drives wind-driven ocean circulation --Average annual precipitation is affected The Gulf Stream is part of the ocean circulation. Louisiana has a similar climate as Southeastern Asia. Warm Temperate climates have crocodiles, palms and mangroves. -Crocodiles go back to the middle cretaceous period. Cenozoic Time Scale: Cenozoic is divided up into two periods: Quaternary and Tertiary. Then they divided up Tertiary up into Neogene and Paleogene. Epochs:

Holocene—entirely recent Pleistocene—most recent Pliocene—more recent Miocene—less recent Oligocene—few recent Eocene—dawn of the recent Paleocene—early dawn of the recent Tropical—warm and wet Cool Temperate—cool and wet Warm Temperate—where crocodiles live Arid—warm and dry (deserts) Cold—cool and dry (ice/glaciers) Key Aspect of Historical Geology is the Record of Life on Earth Classification of Life: Producers vs. Consumers : whether life form creates its own food ( autotrophs ) or dependent on another life form/organic matter for food ( heterotrophs ) Producers : --photosynthesis —carbon dioxide, water, and sunlight (energy needed to drive chemical reaction) produce organic matter and oxygen --chemosynthesis —carbon dioxide, hydrogen, and the energy from a chemical reaction produce organic matter, methane (byproduct), and water; can live in dark places Consumers : -- Respiration —after we eat this process occurs --Eat organic matter --Breath oxygen --Produce carbon dioxide, energy, and water vapor Basic Building Block of Life: Cell —some have a nucleus which houses DNA (humans); others don’t have a nucleus and the DNA is scattered throughout the cell

- Karyon= nucleus -Eu= true -Pro =before -Eukaryotes= have a nucleus -Prokaryotes =have no nucleus Kingdoms of Organisms: Prokaryotes (single cell) Kingdoms:

1. Archeobacteria = “old;” most primitive life forms --Extremophiles =live in extreme environments (either hot or cold or acidic environments) -- Producers or consumers
2. Eubacteria= “true”

-- Producers and consumers --Cyanobacteria= creates a blue color in their environment -- Need sunlight

- -Live on the surface of human bodies and in intestinal tract (over 10% of dry weight of mammals are eubacteria) Eukaryotic Kingdoms:

3. Fungi --Consumers --Mushrooms (multicellular); yeast (single celled—make alcohol, bread, cheese) --Decomposers—involved in decomposition in organic matter
4. Plants --Producers --Photosynthesis --Multicellular --Classificationvascular (tubes) vs. non-vascular (coating on rock like moss) reproduce by spores or seedsproduce flowers or not
5. Animals --Consumers --Multicellular --Invertebrates (no spinal cord—sponges, corals, worms, arthropods=”jointed leg”) vs. vertebrates (spinal cord—fish, amphibians, reptiles, mammals)
6. Protists --Everything else --Most are unicellular --Some are plant-like (photosynthesize) --Example is algae (diatom) --Some are animal-like (consumers) --Example is amoeba (foram) All six kingdoms are well represented in the fossil record. Kingdom Nucleus ? Unicellular ? Multicellular ? Consumer/ Producer? Archeobacteri a No Yes No Both Eubacteria No Yes No Both Fungi Yes Yes Yes Consumer Plants Yes No Yes Producer Animals Yes No Yes Consumer Protists yes Yes Yes Both Power Point Portion of Notes: VolcanoExplorer: http://dsc.discovery.com/convergence/krakatoa/virtualvolcano/virtualvolcano.html Climate Proxies: whether the leaves found in fossil record have jagged or smooth margins?

Paleoclimate Maps: created by Chris Scotese Did climate change during the Mesozoic and Cenozoic? -Climate changed continuously during the Mesozoic and Cenozoic; geologic fact Did the climate changes which did occur during the Mesozoic and Cenozoic limited to a specific area of the Earth? -No, all areas of the Earth experienced a continuous change in climate. Local Example: Louisiana, deposition of the Louann Salt in the Middle Jurassicarid conditions and isolated ocean basin lead to Louann Salt What conditions favored deposition of Louann Salt during the Jurassic? -Two conditions: a restricted ocean basin and an arid climate What was the climate like in LA after Jurassic? -Became warm temperate Life and Fossils: Chapter 4 Classification of Organisms: Study of the classification of organisms: Taxonomy Kingdoms are divided up into: -Phylum -Class -Order -Family -Genus Homo=”human” -Species Sapiens=”wise” Biological Species is a group of organisms that can interbreed and produce fertile offspring. Paleontological Species : ancient species inferred from preserved physical traits Types of Fossils and How They Form: Fossil=any evidence of ancient life; could be a footprint, chemical, or skull Babcock: any evidence of life pre-Holocene; younger evidence than pre-Holocene is considered a subfossil

1. Body Fossils —remains of ancient organisms or something that tells us what the organism looked like (ex. shell; leaf impression) 2. Trace Fossils —evidence of activity of ancient organisms (dinosaur tracks—how far apart tell whether running or walking; worm burrows) 3. Biomarkers —most elusive; chemical fossils (fatty acids; pigments—chlorophyll) How Body Fossils Are Formed: Not everything that is living today will be preserved as a fossil. Study of the processes of fossilization is taphonomy (means “burial study”) living organism

dead organism soft parts (could be eaten and/or decomposed by bacteria; to be preserved rapid burial has to occur or there has to be no oxygen or a very salty environment) hard parts like shell and bone (could be dissolve or erosion could occur; or they could be buried) Taphonomic filter==???need to look in book to find???? Forms of Alteration of Dead Organism Body Fossil

1. Recrystallization— replacement (wood can be replaced with silica)
2. Formation of Molds and Casts —don’t see original material, but there might be a mold or cast left behind
3. Permineralization —filling in of pore spaces
4. Carbonization —organic matter has oxygen and hydrogen driven out of it and all that is left is carbon (wood turns into coal if all that is left is carbon) Power Point Portion of Notes: Archaebacteria can be in the form of slime and hydrothermal vents which perform chemosynthesis. Eubacteria are E. coli and decomposers of animal dung; cyanobacteria create stromatolites. Fungi are decomposers and example is Ordovician fungal spore. Plants can be mosses, ferns (leafy and reproduce with spores), conifers, or flowering plants. Plant-like protist: diatom Animal-like protist: foram Multi-cellular protists: algae What is a coprolite? --Fossil dung (“dung stone”) What is a foram? --An animal-like protist that can’t produce its own food Environment —that which surrounds us -Physical aspects: temperature, rain -Chemical aspects: oxygen, no oxygen Ecology : Eco=”house”; study of environment Diversity of life forms: number of different species in an environment, high diversity in a rain forest Food Chain —food web Example: nutrients (elements essential for life such as carbon, nitrogen, and phosphorus) =energy producers (plant)-------------------------------------- consumer (herbivore can be like a rabbit)------ Decomposers (bacteria, fungi) consumer (carnivore can belike a fox)----------- turn back into nutrients

If you don’t have one link, then the other links can’t function properly. Ecological Niche : position of a species in an environment --where is it? (habitat) --what does it do? produce food? herbivore? carnivore --Example: polar bear--cold environments, carnivore, could be more than one species of polar bear in the same ecological niche Earth History: 3 Major Themes :

1. Physical Evolution of the Earth which we will call Plate Tectonics
2. Evolution of the Earth’s Climate: Atmosphere
3. Evolution of Life Forms **Geologic Time Revisited:
4. Phanerozoic
5. Proterozoic
6. Archean Precambrian
7. Hadean**
8. Age of the Earth: 4.6 BY; before the Hadean
9. Oldest Rocks: 4.3 BY; between the Hadean and Archean
10. Beginning of Modern Plate Tectonics: 2.3 BY; between the Archean and Proterozoic
11. Beginning of Life with Shells: 0.5 BY; between the Proterozic and Phanerozoic Age of the Universe: --Astronomers say it is 15-18 BY Age of our Galaxy: --Astronomers say it is less than 10 BY Age of our Sun: --Astronomers say it is 4.6 BY Star  Supernova (catastrophic expansion) Solar Nebula (collapses into this) Sun and Planets (solar nebula cooled)=pretty quick process Where does the age of earth come from if the age of the oldest rocks isn’t that old? --It comes from the oldest meteorites which date back to 4.6 BY. Formation of the Earth :
12. Accretion of Solids—particles glob together; mostly homogeneous and composed of space debris
13. Heat from Radioactive Decay—Potassium, Uranium, Thorium, and Aluminum 26 (heat reducer) contributed to this heat
14. Earth Melts—two liquids formed: iron liquid (more dense and becomes core) and a silicate liquid (becomes mantle)
15. Basaltic Crust Forms—top layer of earth is formed

5. Formation of the Moon—50 MY after crust formation; hypothesis that the earth’s orbit was inhabited with a mars size planet called Theia (in Greek mythology she gave birth to the sun and moon) which eventually collided with earth; most of Theia is absorbed by the Earth and a molten blob composed of Theia and Earth is thrown into space and becomes our moon Power Point Portion of Notes: Archean age rocks can be found in Minnesota and Canada. Iron meteorites—can’t date well Allende meteorite 1969—contains organic matter and diamonds that can be dated; 4.5 BY is what Allende dates the birth of earth as; can even buy a piece of the meteorite Moon’s core is smaller in portion than Earth; impact events during the Hadean can be seen on the Moon Who is Harrison H. “Jack” Schmitt of Apollo 17? --The only geologist to visit the moon Evidence of cratering on Mars. What did it look like during the Hadean? Two opposing views: molten earth view and then a cool earth with water looking towards a hot moon --Evidence from to support the water view: Zircon --Oldest known mineral grain was zircon and dated 4.4 BY; discovered in Wisconsin --Oldest known rock was found on Hudson Bay and again supports water theory What is the age of the oldest known rocks? --Approximately 4.3 BY Where are they found? --Eastern shore of Hudson Bay