GEOL 102 1st EditionFinal Study Guide Lectures: 1 - 16Week 1: Plate Tectonics and Rocks1. Name and describe the three types of plate boundaries? Sketch a picture of each one. Which createcrust? Which consume crust? Mountain ranges are associated with which type? 2. Define mineral.A mineral is aninorganic solid withorderly arrangementand defined chemistry3. What are the threetypes of rocks? How are they formed?Igneous: solidification (freezing) of molten rock or meltSedimentary: detritus from pre-existing rocks by weathering orbreakdown, then a deposition and lithification of materialMetamorphic: a change in mineralogy, composition, and structure without melting4. What is a common physical difference between extrusive and intrusive igneous rocks?Intrusive rocks were formed at depth within the Earth and have large crystal sizesExtrusive rocks were formed at Earth’s surface and have fine-grained textures5. Why is oceanic crust typically young relative to continental crust?Crust is created at divergent mid-ocean ridges. Crust gets older as you move away from the mid-ocean ridges, since it is being pushed away by the newly created crust. 6. What happens to rocks in order for them to become metamorphosed?Heat, pressure, and fluids cause instability in minerals7. What is a hotspot and how are they used to determine plate motions?Hotspots are volcanoes occurring not along plate boundaries, they develop mantle plumes of hot, rising rock.Plate motion carries volcanoes away from the fixed plume, showing a track in the direction the plate moves.8. Wegener’s theory of continental drift was based on what evidence?The fit of the continental coastlines, glacial deposits, geologic evidence of climatic zones, fossil evidence (distribution along now-far coasts)9. What are the lithosphere and asthenosphere?The lithosphere is the upper portion of the mantle and the crust- it is brittle and breaks under stress.The asthenosphere is below the lithosphere and flows.10. What are mid-ocean ridges?Convergent Boundary: plates move towards one another, crust is consumed, mountains form Transform Boundary: plates sliding past one another, crust isneither created nor consumedDivergent Boundary: plates are moving away from one another, crust is created at mid-ocean ridgesWhere two plates diverge, magma upwells and cools, creating new crust; this pushes the older sea floor away from the ridge11. Where do earthquakes and volcanoes tend to occur (with respect to plates)?Subduction zones (convergent plates) are the locations of the largest earthquakes and arc volcanism.Earthquakes also occur along transform boundaries. 12. How did the Himalayan mountains form?Continental collisionThe Indian subcontinent collided with Asia, the crust was crumpled and uplifted.Week 2: Geologic Time1. In the 1600s, our notion of geologic time was based on what?Biblical scholars 2. What is uniformitarianism?Processes in action today also were acting in the past.This indicates a slowness of geologic processes.3. What is an unconformity? What are the three types? Sketch each one.Unconformities are gaps in the geological record.4.How do fossils aid in ourreconstruction of geologic time?Fossils present in certain beds butnot those above them give therelative ages of the rock beds.5. Describe the law of superposition? Other laws (principles) of relative dating?Superposition: layers towards the bottom are the oldest, each successive layer is younger as you go upOriginal horizontality: layers are likely laid down horizontally and parallel to the EarthOriginal continuity: beds are laid down the same across spaceNonconformity: sedimentary rocks overlie igneous or metamorphic rocksDisconformity: parallel sedimentary beds separate an erosion surface (can be hard to tell)Angular unconformity: rocks aretilted or folded before erosion and further depositionCross-cutting relationships: what cuts through layers is younger than what it cuts 6. Describe the process of radioactive decay. Parent isotopes decay into daughter isotopesDecay begins when rocks cool to lower than the blocking temperature, when isotopes can no longer escape the crystal lattice 7. How are isotopes different from standard elements?Naturally occurring isotopes are elements with different atomic weights (protons and neutrons), its weight is different than a standard isotope, and because of that they’re unstable, which makes them able to decay and breakdown8. What is the half-life of a radioactive isotope?The half-life is the time needed for half a group’s isotopes to decayThe key for measuring is determining the ratio of parents to daughters and comparing this with the half life9. Why do we think the earth is older than the oldest rocks found on its surface? How has the moon assisted in our determination of the age of the earth?Rocks on the Earth are constantly being recycled, the current oldest are ~4.3 billion years oldMoon rocks were formed at the same time as Earth, and they are not involved with tectonic activity. They are 4.4-4.5 billion years old10. What is the age of the Earth?4.57 billion years oldWeek 3: Water and the Hydrologic Cycle1. How much of the Earth’s surface is covered by water?70%2. Describe the origin of water on earth.Carbonaceous chondrites (~20% water) (meteorites) landed on Earth, are constituents in clay materialsHeat generated during the planet’s formation released water vaporThe primitive atmosphere released other gasesWhen accretion slower (4.5 billion years ago), the Earth’s surface began to coolLiquid water accumulates all over the surfaceMeteors continue to land on Earth until 3.5 billion years ago3. What is the hydrosphere? How has the amount of water in the hydrosphere changed over the earth’s history?The hydrosphere is a measurement of water on Earth from the ocean’s bottom to the troposphere (15 km elevation)It holds 1.36 billion cubic km of water, this amount has remained relatively constant over time4. What happens to water molecules when vapor is changed to liquid water?During the gas to liquid phase change, hydrogen bonds form (and break and re-form)5. What physically happens to the structure of water molecules when frozen?The bonding angles increase, which decreases the densityIt becomes geometrically aligned into a hexagonal pattern6. How does the density of water change when it changes to ice?The density decreases when it becomes ice- it forms into a hexagonal crystalline structure, and has more empty