Science and Pseudoscience 1. What is science? Be able to distinguish scientific claims from non scientific ones. 2. Scientific Method - data, hypothesis, predictions, theory, laws; models, experiments 3. Understand the basic differences between scientific claims and pseudoscientific ones. Know the general symptoms of pseudoscience. Minerals 1. What are the most common elements (and minerals) in the earth’s crust? Elements: Silicon, Oxygen, Magnesium, Aluminum, Iron Minerals: Quartz, Biotite, Feldspar,Halite, Gypsum, Pyrite, Diamonds, Ice, 2. Give a basic definition of a mineral. How do minerals differ from rocks? a mineral is naturally occurring, inorganic solid substance with a specific chemical composition and crystalline structure. Minerals are the building blocks or “ingredients of rocks, one or more minerals make up a rock. 3. Understand the basic properties that we used to identify minerals. For example, what is the difference between cleavage and fracture? Identify cleavage where it occurs (incl. how many planes/angles) Properties used to identify below: 1. Luster: Metallic or nonmetallic (shiny doesn’t necessarily mean Metallic) 2. Hardness: The resistance of the mineral to scratching. Hardness greater than 6 will scratch the glass 3. Cleavage and Fracture: (When a rock exhibits cleavage, it breaks into flat, smooth pieces or sheets.)If they don’t break along predictable planes, the mineral exhibits fracture. Fracture refers to the way a mineral or rock breaks when it does not follow a cleavage plane. Fracture surfaces are usually rough and irregular, lacking the smoothness and regularity of cleavage planes. 4. Streak- is the color of the mineral in powdered form. ( rub against porcelain place and examine the color of powder left behind. 5. Color: is another physical property that can help identify a mineral. 4. Be able to identify some of the more common rock-forming minerals. Ex: Quartz, Olivine, Magnetite, Halite(table salt), Mica, Garnet, Pyrite, Biotite,etc… Igneous Rocks 1. What is the difference between magma and lava? Magma is molten rock below ground and Lava is molten Rock above ground. 2. How are igneous rocks classified? They are based on two parameters. 1. Texture- Crystal Size and arrangement, function of cooling history 2. Composition-Minerals that form the rock How do they form? Igneous rocks are formed when molten magma or lava cools and solidifies. This process happens deep within the Earth or on the surface during volcanic eruptions. Be able to name and discuss the major examples we looked at in class. Extrusive: Rhyolite, Andesite, Basalt Intrusive: Granite, Diorite, Gabbro, Peridotite 3. Know the difference between plutonic (intrusive) rocks and volcanic (extrusive) rocks. We refer to rocks that form underground from magma as PLUTONIC or INTRUSIVE. Rocks that form from Lava are VOLCANIC or Extrusive 4. What does having a porphyritic texture tell us about the history of a rock that has it? Porphyritic Texture: Has 2 different grain sizes(big (coarse) and small(fine) crystals). This is because of 2 cooling rates-mixed first slow and then fast. 5. How are igneous rocks/magma of granitic (silicic) composition different from igneous rocks/magma of basaltic composition? Igneous rocks of granitic (silicic) composition and basaltic composition differ in several ways, including their mineral composition, color, texture, density, and the tectonic settings in which they form. Granite-Magma Basalt - Lava Plutonism and Volcanism 1. What are dikes, sills, and batholiths? Batholith- Batholiths are large, intrusive igneous rock formations that form deep within the Earth's crust. They are characterized by their massive size and represent some of the largest and most extensive plutonic bodies on Earth. Batholiths are typically composed of granitic intrusive bodies DIKES and SILLS are Tabular intrusions (Look like a tablet). Dikes cut across and Sills run parallel to pre-existing rock. 2. How do we find batholiths (that formed underground) exposed at the surface? Uplift and Erosion: Over time, tectonic forces can uplift large sections of the Earth's crust, bringing deep-seated batholiths closer to the surface. As the uplifted area is exposed to weathering and erosion, the overlying rocks are gradually worn away, eventually exposing the batholith at the surface. EX: Half Dome, Sierra Nevada Batholith 3. What are the three types of volcanoes? Composite (stratovolcano) - Andestic and Dacitic (more silica, rich lava) Mount Hood and Mt. Shasa Shield Volcanoes- eruptions are not explosive (the silhouette looks like a shield) Cinder Cone- Small pyroclastic cones Be able to give an example of a shield volcano or a composite cone. Be able to sketch different volcano types. Composite-Mt. Hood and Mt. Shasta (pointy cone) Shield Volcano- Mauna Loa (looks like a shield) Cinder Cone-Mt. Pinatubo (looks like an ant hill) 4. Where in the world might you find these volcanoes – tectonically and geographically? 5. How do the types of volcanoes differ in terms of composition, eruption behavior, and the hazards they present to people? Composite- Explosive, rich lava Shield- runny lava, low viscosity, not explosive Cinder- very small in relation to the other two. 6. Be able to discuss volcanic hazards and cite one or two important historic eruptions. 7. How do scientists try to predict the timing of a volcanic eruption? What kinds of data do they use? Sedimentary Rocks 1. What are the major types of weathering? Two Major Types of Weathering= 1.Chemical Weathering- Water, acid, oxidation, etc. Faster in warm humid climates than in dry ones. 2.Mechanical WeatheringPhysical breakdown of rocks, ice-wedging, plant roots, agents of erosion, expansion due to pressure release (e.g., Half -Dome). 2. How does climate influence chemical weathering? Weathering and Climate= Cold, dry climates produce the slowest rate of weathering. Hot, wet climates produce the fastest weathering. Global Warming increases the rate of Chemical Weathering by causing more rainfall and speeding up the chemical reactions between rainwater and rock. “Chemical weathering is caused by rain water reacting with the mineral grains in rocks to form new minerals (clays) and soluble salts. These reactions occur particularly when the water is slightly acidic”. 3. What are the agents of erosion and which one is the most important on Earth. The Agents of Erosion= They have to be able to break down rocks/sediment physically -And move them (transport) to another place. The 4 Agents are: 1.Gravity 2.Ice 3.Running Water (the most important). 4.Wind 4. How do the major types of sedimentary rocks form? What are some examples? -See images below: (Not sure why it’s circled green, image was found that way). 5. How are sedimentary rocks classified? Be able to identify examples. 1.Clastic/Detrital- Fragmental. 2.Chemical/Inorganic- Crystalline. 3.Organic/Biogenic- Bioclastic. (Example in image from #4, as well as the image below). 6. How do you turn a bunch of sediment into a sedimentary rock? Describe the sedimentary cycle. -Sediment Cycle= The entire cycle can repeat, or parts of the cycle can repeat. 1.Weathering and erosion- Creates sediment. 2.Transportation- Sediment gets moved. 3.Deposition- Clasts are dropped/settle out. Lithification turns settlement into rock. 4.Burial- Buried by other sediment. 5.Compaction (part of lithification) - As more sediments accumulate above, clasts are forced closer together. 6.Cementation (part of lithification)- Groundwater moves between the grains and leaves behind mineral deposits, bonding the grains to each other. 7. What do sedimentary textures (grain size, sorting, and rounding) tell us about the energy of the environment of deposition or transportation? Or about how long a sediment grain has been in the sedimentary cycle (erosion - transportation - deposition - erosion, etc.)? Sediment Maturity • Function of: – Distance transported – How many times through the cycle – Maturity tends to increase • Textural Maturity – Sorting, grain size, rounding • Compositional Maturity – Increase in minerals resistant to weathering ^^High energy= Fast. Low energy=Slow^^ Metamorphic Rocks 1. How do metamorphic rocks form? Be able to describe contact and regional metamorphism. - - - How: Agents of Metamorphism - Heat - pressure - chemically active fluids Contact Metamorphism - Heat and fluids are main agents - not much mechanical deformation Regional Metamorphism - not localized: regional in scale - pressure and heat are primary agents - deformation may occur as well - CONVERGENT BOUNDARIES are a good place to see regional metamorphism 2. Be able to identify and discuss examples. - Foliated Rock - layers - increase w/grade of metamorphism - high grade metamorphism = unrecognizable from parent rock - low grade = similar to parent rock - - often result of regional metamorphism - EXAMPLE: Protolith = Shale - Slate: lowest grade - Phyllight: still fine grain/shiny sheen - Schist: course grain / shiny - Gneiss: course grain/banded Non-Foliated - everything else - EXAMPLES: - Quartzite: metamorphosed quartz sandstone - Marble: metamorphosed limestone - Metaconglomerate - Serpentinite: metamorphosed ultramafics - Anthracite Coal 3. Why do many metamorphic rocks form layers (foliation)? - In metamorphic rocks layers (foliation) occurs when pressure squeezes and elongates the minerals (typically micas) so they become aligned. The Rock Cycle 1. Be able to fully diagram the Rock Cycle * TO GET FULL CREDIT MUST INCLUDE EXTRA (logical) LINES * The Earth’s Interior 1. Name and describe the layers of the earth’s interior. What are their physical properties? Oceanic Crust- Thin, composition equivalent to Basalt Continetal Crust- Thick, compostion equivalent to granite, thicker under mountains The mantle- thickest layer, 82% earths vol, 65% earths mass, divided into upper and lower mantle The core- density of the earth 5.5 g/cm^3, core must be really dense, Nickel Iron fits the bill The Earth’s Interior- Crust: solid two “flavors”, rigid/brittle, very thin layer Mantle: solid, plastic/ductile, weak- can flow Outer Core: liquid, nickel-Iron (Ni-Fe)e Inner core: solid, Ni- Fe 2. How do we know about these layers and their physical properties? Seismic waves- Primary waves: fastest compressional travel thru all layers Secondary waves: up-down/side to side cannot travel thru liquids Seismic wave behavior: if a wave passes from one layer to another with a different density, the wave may: 1) change velocity 2) refract (bend - think prism) Continental Drift and Plate Tectonics 1. Summarize the evidence that Wegener used to formulate his Theory of Continental Drift. -He argued that all the continents were once unite as a single supercontinent, he called “Pangea”, that existed more about 200-300 million years ago -jigsaw fit of the continents -fit of mountain ranges with rocks of right age -fossil evidence, certain fossils in certain areas -ancient glacations leave behind tell-tale marks 2. Summarize the evidence that supports Plate Tectonics. -fossil evidence -clues left by glaciers -records in rock -complimentary coasts , they fit together like a puzzle 3. Name and discuss the three types of plate boundaries. Give examples of each one and summarize how they work and what their key characteristics are. Be able to sketch and label a cross-section through a plate boundary (see Homework #8). - Divergent (plates move apart) - Convergent (plates move together, collisional) - Transform (plates move past one another) 4. Know your own backyard (in a very general sense), tectonically speaking. -San Andreas fault - All of Northern california is made of accelerated terranes, added in the past 200 million years 5. How are oceans created? Destroyed? - New oceanic crust and new oceans forms at mid ocean ridges (divergent boundary), as well as shallow earthquakes - Destruction of oceanic crust and new oceans are at the ( convergent boundary) 6. What are hotspots and what kind of information can we get from them? Can you give an example? - “A chain of volcanoes forms as a tectonic plate moves over a plume of hot mantle material rising from deep within earth” - Chain of explosive super volcanoes - Yellowstone hotspot Faults and Earthquakes 1. Understand the physics of earthquakes. e.g., the Elastic Rebound Theory - blocks move gradually or in jerks (ave. cm/yr) - friction sticks them together, so the rocks near the fault bend (strain) - as strain accumulates in the rocks - potentially energy accumulates - rocks try to unbend, exerting a force on the fault, trying to cause fault slip - - - but friction keeps the rocks stuck together Finally friction is overcome and the rocks suddenly slip along the fault - strain is released (the rocks unbend) - potential energy is released (ground shaking) Afterwards, the two blocks are unbent but off set - the parts along the fault have caught up with the parts of blocks far away from the fault 2. What is the difference between a focus and an epicenter? - Focus: inside the earth’s crust. where the earthquake originates - Epicenter: the point on earth’s surface directly above the focus 3. What are the different types of seismic waves and how do they differ from one another. - - surface waves - created by interference from reflected body waves - Love and Rayleigh waves - more complex rolling motions / greatest amplitude body waves - Primary (P) waves: fastest, compressional, travels thru ALL layers - Secondary (S) waves: up/down, side-to-side, CANNOT travel thru liquids 4. What are the different types of faults and how are they related to stress? - Dip Slip: Motion is vertical - - - normal faults - Hanging wall down, Footwall up - result of (Ex)tensional Stress thrust or reverse faults - Hanging wall up, Footwall down - result of compressional stress Strike Slip: Motion is horizontal - right or left lateral - - SAN ANDRES FAULT IS RIGHT LATERAL STRIKE SLIP FAULT result of shear stress 5. How do we measure an earthquake's magnitude? Intensity? - Magnitude: Moment Magnitude - more accurate determination of energy released - similar to Richter Scale but adjusts for - length of ground rupture - - duration of shaking - rigidity of crust Intensity: Modified Mercalli Scale - measures earthquake intensity or damage - locality specific - uses roman numerals I-XII (1-12) - each earthquake has 1 magnitude number but can have multiple mercalli numbers - applies directly to hazards 6. Be able to list or describe earthquake hazards. - Fire *BIGGEST HAZARD* : - ground shaking - liquefaction: happens in wet fine soil. Soil particles lose cohesion as they shake (solids act as a liquid). dense things sink/low density floats - resonance effects - ground rupturing: not a huge danger - uplift - landslides - tsunamis: when the seafloor is disrupted 5. What factors determine how devastating a particular quake will be? Apply these factors to the 1989 Loma Prieta earthquake. - Severity Factors: - magnitude - - location - geology underfoot: denser ground = less shaking - preparedness - duration of shaking/aftershocks - depth - building qualities/designs: older/less-well builds fail 1989 Loma Prieta Earthquake - 5. What cities in the U.S. are at danger from an earthquake? Those along the fault lines. Specifically Alaska, Hawaii, and cities on the West coast. two major fault lines (San Andres & Juan de Fuca) run along this part of the US.
