Earth Exam Study Guide

Exam 1:,m Unit 1. Earth’s Formation: Define stellar nucleosynthesis and explain its significance: - Stellar nucleosynthesis is when fusion in stars creates larger atoms. - This process is significant because it allows new elements that were not created in the big bang to form. Earth and planets forming: - Planets form by getting a lot of dust and gas close enough to each other to create a gravitational field strong enough to start fusion, fusion creates energy which stems the creation of stars. - The surface of earth initially magma ocean and then began to cool + solidify. - When Earth formed, the layers were not well defined as everything was molten rock. However, the Earth cooled and heavy materials like iron sank to form the core, and lighter materials like silicates rose to form the crust. Unit 2. System Earth: Makeup of Earth: - Crust: oxygen (O), silicon (Si) and aluminum (Al). - Earth as a whole: iron (Fe), oxygen (O) and silicon (Si). - Layers of Earth (inside -> out): o Inner core: completely solid (smaller then outer core) o Outer core: liquid o Mantle (3 parts) (takes up most space)  Mesosphere lowest layer  Aesthenosphere 2 nd lowest layer  Both act as conduction ovens o Lithosphere is rigid + acts a conduction oven to the rest of the earth o Crust  Continental + Oceanic (continental is thicker) Magnetic fields of earth - Generated by the motion of molten iron in Earth's core, the magnetic field protects our planet from cosmic radiation and from the charged particles emitted by our Sun. Unit 3. Plate Tectonics: Seafloor Spreading: - Seafloor spreading is when divergent plate boundaries move away from each other in the ocean. Mantle flows to this point and cools forming new crust. There are 3 proofs of this: o Deep sea trenches o Fracture zones (narrow, vertical cracks in ocean surface) o Seamounts (volcanic islands) Divergent, Convergent and Transform: VOLCANOES EARTHQUAKES TOPOGRAPHY

DIVERGENT (going away) Volcanic activity Shallow earthquakes Oceanic spreading ridges, red sea rift, (ridges and rifts) CONVERGENT (coming together) one plate dives under another resulting in a line of volcanoes on the overriding plate, 80% of earthquakes take place on convergent boundaries Caribbean islands, Himalayan mountains, Appalachian Mountains, (large risings in ground or ocean) TRANSFORM (slide sideways) Little to no magma available at plate boundaries meaning that volcanoes do not typically form Most dangerous and largest earthquakes (San Andrea's fault is transform earthquake) Long ridges separated by narrow valleys (much of California is on a transform fault) - Connecticut was part of Africa but plate tectonics rifted it away and made the Atlantic Unit 4. Minerals: The major class of rock forming minerals are silicates (silicon and oxygen) Examples: Quartz, Feldspar, Mica, Clay minerals, Olivine, Garnet, Pyroxene, Amphibole, Beryl, Hemimorphite, Epidote WHY Minerals form o Atomic bonding + size constraints o Specific minerals form based on pressure temperature and composition o Atoms bond and fit together in minerals to minimize potential energy of the system o Nature trends toward minimizing energy and attaining equilibrium HOW minerals form o precipitation, dissolved in aqueous solution -> solid o solidification, magma or lava -> solid o diffusion, solid -> solid o De-sublimination, vapor - > solid o biomineralization there are classifications of rock forming minerals o Silicates, Carbonates, oxides, halides, sulfates, sulfides, native éléments Unit 5. Rocks: - 3 ways to melt a rock o Increase temp o Decrease pressure o Add volatiles (ex. Water) – COMPOSITION! (put in the melt chart) once you cross the solidus, melt forms

- Six types of igneous rocks COMPOSITION FINE GRAINED (EXTRUSIVE) COARSE GRAINED (INTRUSIVE) FELSIC Rhyolite - Red-Orange Granite - Array of lighter colors INTERMEDIATE Andesite – Gray Diorite - Half dark/Half white MAFIC Basalt – Black Gabbro - Dark gray/Black - A foliation is any planar fabric in a metamorphic rock (Similar to layers of a biscuit) o Foliation is due to differential stress o -

- - - Unit 6. Fossils + Life on Earth: When and where did the first life form? Life on Earth is about 3.7 billion years old. It formed at deep sea hydrothermal vents. Here, seawater meets magma to form microorganisms. Stromatolite and banded iron formation: - Banded iron formations form when iron is oxidized and forms rust. - Stromatolite are layers of bacteria trapped in layers of sediment - These are significant because they are proof of the first oxygen on Earth. Stromatolite are the first photosynthesizing things on Earth. Unit 7. Sediments: - Physical vs Chemical Weathering o Physical: breakdown of rocks and soil through mechanical effects o Chemical: breakdown via chemical reactions - Wind + Gravity + other agents can move clastic sediment o Sediments are deposited when the forces of gravity overcome those trying to move them o As energy of transportation decreases smaller material is deposited How do clasts (a kind of sediment) change? They get smaller, rounded, and well sorted as they move

Identify the depositional environment of common chemical and biochemical sedimentary rocks (rock salt, travertine, coal, chalk, limestone). - rock salt = large enclosed bodies of seawater and desert- - travertine = springs - coal = delta, swamp - chalk =deep marine - limestone = ocean, sometimes lake Unit 8. Time:  Angular unconformity - uplift and erosion -> limestone folded and eroded o Flat layers overly tilted layers  Disconformity – uplift and erosion -> deposition of new sediment o Flat layers overlie flat layers  Nonconformities – uplift and erosion exposed igneous metamorphic rock -> sediment deposited on topz - Contact metamorphism: magma intrudes and changes rock. Intruding magma is younger - Cross cutting relationships (intrusions) means that the intrusion is youngest thing there - Compressive stress = folding = converging plates Unit 9. Mass Extinction - Warming of the Earth's climate and associated changes to oceans caused end-Permian extinction - MASS EXTINCTIONS INVOLVE COMPOUNDING EFFECTS - End-Permian Mass Extinction o 1. Carbon Dioxide (volcanic emissions) o 2. Warming o 3. Ocean acidification o 4. Ocean anoxia o 5. Desertification o 6. Climate Change o 7. Habitat loss o 8. Acceleration of "normal" extinction mechanisms o = 96% of all species extinct - heightened volcanism associated with the Deccan Traps and the Chicxulub asteroid impact caused the end-Cretaceous extinction Unit 10. Climate - The Greenhouse effect o Radiation from sun travels to earth o Half reflected or absorbed by clouds and atmosphere o Rest reaches earth and absorbed by ocean and land o Earth releases heat (infrared light towards space) o Some of this heat passes directly thru atmosphere o Most is captured by ghg and heats atmosphere - Volcanism vs weathering