All Big Picture Aspects Unless Otherwise Stated Study Guide

ALL BIG PICTURE ASPECTS UNLESS OTHERWISE STATED ADD THE STUDY GUIDE FOR NEW SECTION AS WELL ❖ Scientific Method: Is a sequence of steps for systematically analyzing scientific problems in a way that leads to verifiable results ● 4 parts: 1. Recognizing the problem 2. Collecting Data 3. Proposing Hypothesis 4. Testing Hypothesis ● Hypothesis: A “proposed” explanation for a specific problem. - Has explanatory power and can be tested by further investigation. - If you can’t test it then it isn’t a hypothesis. - Happens in the testing idea phase ● Theory: A scientific idea supported by abundant evidence, they have passed many tests and haven’t failed any. - Scientific theory: A widely accepted explanation for why things work the way they do. Greater breadth than hypothesis ● Data: systematic collection (exact), NOT anecdotal information (like me telling you something meaning I could lie) and a direct observation is NOT needed - Data: information gleaned from observations – usually observations that are made in a standardized way. Systematic collection, NOT anecdotal information and a direct observation is NOT needed ● Scientists spend MOST time in the gathering/interpreting data ● MOST IMPORTANT part of the scientific method is the community analysis and feedback part; however it Is the least known method by an average person ❖ Major Rock Types and Where They are Found ● 3 Major Rock Types: ● Sedimentary: Made from sediment (bits of rocks) - Sedimentary rocks form in banks of rivers, bottom of mountains, deep oceans - Sedimentary rocks forms at or near the earth’s surface in one of several ways: by cementing together loose clasts produced by physical or chemical weathering of preexisting rock; by the growth of shell masses or the cementing together of shells and shell fragments; by the accumulation and subsequent alteration of organic matter from dead plankton or plants; or by the precipitation of minerals from water solutions - Divergent plate boundaries (mid-ocean ridges) Convergent plate boundaries (mountains) Found in: o Glaciers o Mountain streams o Alluvial fan o River o Lake o Sand dunes o Coastal beach o Deep ocean o Bottom of mountains ● Metamorphic: Rocks changed by heat or pressure - Solid state change = NO melting involved - If melted = igneous - Diagenesis: deeply buried sediment o Increase pressure and temperature new minerals form o Sedimentary rocks + increase temperature = metamorphic - Where does Metamorphism happen o Contact metamorphism: existing rock heated by intruding magma o Regional Metamorphism: associated with mountain building, rocks bash together with pressure and rise up to make mountains o Burial Metamorphism: very deeply buried sediment o Dynamic Metamorphism: fault zones and transform boundary (no melting) o Subduction zones (convergent boundary) o Shock: meteorite impact - EX FROM CLASS: Metamorphic forms at a convergent plate boundary - EX QUESTION FROM CLASS: Which type of rock would you see in the middle of a mountain range? – Metamorphic - Metamorphic rocks form at mountain ranges ● IGENOUS: made from magma or lava - “freeze” out of lava or magma - Lava: melted rock outside the earth - Magma: melted rock inside the earth - Igneous rocks are formed by the cooling of magma underground, or of lava at the surface - Igneous rocks are formed at divergent and convergent plate boundaries NOT TRANSFORM - Intrusive igneous rock: in the earth - Where Intrusive igneous rock is found: o o o o o o - When magma chambers cool and turn into: Pluton (EX: stone mountain) Batholith (EX: El Capitan Cliff) Laccolith (EX: Marcellina Mountain) Sill: horizontal intrusion cools Dike: Vertical intrusion cools (upright) Extrusive igneous rock: outside the earth Where extrusive rock found: o Lava turns into igneous rock when it is in the air/on earth - EX FROM CLASS: Igneous rock forms in volcanoes and volcanoes are located on plate boundaries, mid-ocean ridges, middle of the ocean, subduction zones (island arc and continental arc), continental rift zones, hot spots, flood basalts (large igneous provinces) o Igneous rocks are formed in the following tectonic areas: o Subduction zones: continental arc (Convergent boundary) o Island arc o Hot spots o Continental Rift Zones (Divergent boundary) o Mid-Ocean ridge (Divergent plate boundary) o Large igneous provinces ❖ What Happens at each Tectonic Boundary - Mountain and volcanoes occur everywhere BUT transform boundaries, like at convergent and divergent boundaries - EX: volcanoes, earthquakes, mountain ranges - Divergent: two plates move apart o Mid-ocean ridge: volcanoes o Continental rift: divergent boundary in continent and plates moving away - Convergent: two plates moving towards each other o Subduction zone: the process of consuming a plate and is the reason for earthquakes at plate boundaries o Subduction ocean/continent: ocean plate is always more dense so it will always subduct o Subduction ocean/ocean: the oldest ocean crust will be more dense and subduct o Collision continent/continent: Continental crust cannot sink because it isn’t dense enough so it will go up forming mountains - Transform: two plates sliding past one another and no new plate forms o Mostly ocean/ocean near mid-ocean ridges and sometimes can be continental/continental ● ● o o ● o Faults: fracture in rock where the two sides of the fracture move in opposite directions resulting in displacement o Can cause earthquakes Geological Features - EX: Mountain ranges and volcanoes formed at what boundary? - Mountains form at convergent plate boundaries - Divergent: o Mid-ocean ridge: volcanoes o Continental Rift - Convergent: o Subduction zone: reason for earthquakes o Subduction ocean/continental o Subduction ocean/ocean o Collision continent/continent: mountains - Transform: o faults o No new plates form Rocks - Sedimentary Divergent plate boundaries (mid-ocean ridges) Convergent plate boundaries (mountains) - Metamorphic o Convergent plate boundaries (mountains) - Igneous o Convergent o Divergent Faults - fracture in a rock where the two sides of the fracture move in opposite directions resulting in displacement - Two types: 1. Strike-slip: two blocks of rock move horizontally, parallel to strike of fault o Left-lateral o Right-lateral o Strike-slip = transform boundary 2. Dip-slip: vertical motion in dip direction o Normal = Divergent boundary (tension) and Continental rift zone o If it is a deep normal = convergent o Reverse and thrust = Convergent boundary/subduction zones (compression) o Oblique = transform and divergent ❖ ❖ ❖ ❖ - Faults happen on convergent, transform, and divergent plate boundaries - Faults form everywhere the crust moves - Every plate boundary has a fault - Causes earthquakes How do we Date Rocks ● 2 Major Ways: ● Relative Dating - Name some ways that we relative date: fossils - Does NOT give calendar ages - EX: this thing is older than that thing - Based on logical principles ● Numerical Dating - Name some ways that we numerical date: radioactive decay - Radioactivity can act as a clock - Numerical dating = age given in numbers/years - Radioactive isotopes give the numerical age What do Geologists Study? - EVERYTHING; don’t answer “just rocks” - GEOLOGY: is the scientific study of the composition, behavior, and history of the earth or other planetary body Why is Geology Important? (in Alabama) - Because it is constantly surrounding us and affects how we live - Geology may be one of the most practical subjects you learn, gives you a holistic context for interpreting your surroundings, and puts the accomplishments and consequences of human civilization in broader context. Also, it is important to see how the world was made, to see how it continues to evolve, to find its valuable resources, to prevent contamination, and to predict its dangerous movements. - In Alabama the 3 main minerals are: o Coal - 70% of Alabama’s electricity; 13th nationally o Iron Ore o Oil/natural gas - 16th for natural and crude; brings lots of money from fees/taxes Basics of Earth History ● How old is the earth and universe? - Earth is 4.5-4.6 Ga (billion years old) - Universe is 13.7 Ga (billion years old) ● How do we know? - By relative dating asteroids/the moon - By geological features: grand canyon, coal beds, mountains ● Very General Timeline of Earth History: Mainly DIVERSITY, BIG PICTURE - DON’T need to know eons or eras - EX: earth was created – no land/oxygen – life, land, and photosynthesis helped create oxygen – algae/worms – enough oxygen for people – Cambrian explosion – diversified – giant extinction/ shell creatures – fish – amphibians – reptiles – mammals - EON: 4.55 Ga formation of earth, 4.5 formation of moon, non-oxygen atmosphere, no water, some water, NO LIFE, algae, seaweed, Cambrian explosion: mass diversification – liquid water, not much oxygen in atmosphere, first life, photosynthesis – super continents, enough oxygen in atmosphere for people to live, algae, worms, jellyfish, snowball earth ends period – - ERAS: no life – Cambrian explosion: mass diversification of life – algae – diverse shelled animals – first vertebrate (jawless fish) – diverse shelled life – spiders/insects – 1st amphibian – Pangea forms – amphibian diversity – 1st reptile- largest extinction in history – break up of Pangea – 1st swimming and flying reptiles – 1st turtle – dinosaurs – Pangea broken – 1st flowering plant – modern fish, dinosaurs, mammals – dinosaurs extinct – 1st grasses – giant mammals ❖ What are the Major Fossil Energy Sources? - Coal, Oil, Gas (fossil fuels) ● How Do We Get Them? - By mining - Drilling: puncture rock ● How are They Formed? - Formed over time - Ultimate source of energy in fossil fuels is solar energy - Oil/natural gas: Important forming factors is temperature, time and pressure o Oil window: between 90-160 degrees Celsius o Remains of algae and plankton - Coal: Important forming factors is carbon and pressure o Formed mostly from remains of plant material - None of these are easy to make or preserve! - Non-renewable because the geological places in which they are formed are special; takes millions of years for them to be rebuilt 1. You are expected to know basic terminology in order to answer the questions. Be sure to study your definition sheet from the streams and rivers lecture. 2. What are ores, how do they form, and how do we use them? ● Metallic mineral resources: - Metal: minerals with metallic bonds - Grade: percentage of extractable metal (cost-effective) ● ORES: rocks with high metal content ● Formation of ore deposits: - 1). Magmatic o Partial melting o Settling - 2). Hydrothermal o Hot water dissolves mineral o Deposits when cool - 3). Sedimentary o Chemical precipitation - 4). Placer o Flowing water o Heavy minerals drop o Light minerals carried away ● Use them as gems, building stone, chemicals, salt, sand, and gravel 3. How do we extract mineral resources and what are the drawbacks? ● Mining and drilling ● Drawbacks: - Mine runoff - Groundwater contamination - Acid rain 4. What is the hydrologic cycle? ● HYDROLOGIC CYCLE: circulation of Earth’s water supply ● Oceans – condensation – atmosphere – precipitation – infiltration – groundwater – ocean 5. How do streams erode, transport, and deposit sediment? ● Stream erosion: - Gravity makes water move - Types of erosion: o Sourcing: remove loose fragment o Breaking and lifting o Abrasion o Dissolution - Characteristics that cause the most erosion: o A lot of water o Turbulent: twisting, swirling motion o Sediment (a lot) ● Sediment transport - Sediment load: total volume of sediment carried - Components: dissolved, suspended, bed ● Competence: maximum particle size a stream can carry - High = low particle - Low = smaller particle - Max particle size stream carries ● Capacity: total quantity of sediment a stream can carry – depends on competence and discharge ● Deposition: decrease in velocity that causes sediment to dump out of the water - Gradient change - Friction with bed increases - Velocity change determines sediment size 6. What are the characteristic landforms of stream systems, and how do they form and change? ● Stream anatomy - Long main channels - Tributaries: side channels that flow into the main channel of a stream - Drainage network: a group of interconnecting streams that form patterns reflecting the underlying geology AKA the channel and tributaries together - Drainage networks form pattern reflecting underlying geology - Not static - Watershed: land area contributing water to a stream - Drainage divides: o Many scales of watersheds o Large watersheds: feed large rivers, section continents o Continental divides - Permanent Stream o Water flows all year o At or below water table o Humid or temperature climate - Ephermal stream o Don’t flow all year (flash flood) o Above water table o Dry climate - LOOK UP DEFINTION SHEET ● Typical stream - Valleys and canyons o Land cut by stream o Canyon-steep slope o Valley-gentle slope - Rapids and waterfall o Rapids-rough water o Large debris o Narrow channel o Gradient change - Alluvial fans o Abrupt change in velocity o Stream dumps coarse sediment - Braided streams o Stream divides due to sediment o In between floods - Meandering stream o Moves slowly and really curvy o Flat area o Goes the easiest way Floodplain o Deposits sediment - Deltas o Running water meets standing water o Velocity change – sediment drops o Changing landscapes 7. What are the different types of floods, their causes, the results and how do we measure them? ● Causes of floods: - Sudden heavy rain or snow melt - Water cant soak into ground fast enough - Long period of rain - Ground becomes saturated - Collapse of artificial of natural dam ● Seasonal floods - Gradually covers floodplain - Rainy season - Spring melting ● Flash flood - Quick rise in stream water level - Unusually intense rainfall - Dam collapse ● Recurrence interval - EX: 100 year floods happen about once every 100 years - Average number of years between floods of the sample size - ANNUAL PROBABILITY: o EX: if probability = 1%, then there is a 1% chance of that size flood happening any given year o Relationship: annual probability = 1/recurrence interval o EX: what is the annual probability of a 50 year flood? 1/50 = 0.02 = 2% 8. What effect do humans have on rivers and vice versa? ● Human effect: - Provides transportation, food, irrigation, water, drinking water, power, recreation, and water disposal - Fertile soil for fields ● Environmental issues - Pollution: raw sewage, spilled oil, toxic chemicals, floating garbage, animal waste, etc. - Dam construction: o positive: provide irrigation water and hydroelectric power and they trap some floodwaters and create popular recreation areas o negative: destroys “wild rivers” and alters the ecosystem of a drainage network by forming barriers to migrating fish, decreasing nutrient - supply, removing the source of sediment and eliminating seasonal floods that replenish nutrients in the landscape not increases - Urbanization and agriculture: water is soaked up into crops and fields and less rainfall makes it to streams and rivers when structures are built, concrete, and the like prevent rainfall from seeping into the group storm sewers and streets divert water directly to streams so volume of water entering increases 9. What are the major features of the ocean floor? ● Continental shelf: relatively shallow portion of the ocean that fringes the continent; water depth does not exceed 500 m - Continental crust with ocean on top at moment ● Continental shape: continent and ocean connect ● Abyssal Plain: a vast, nearly horizontal surface. A broad, relatively flat region of the ocean that lies at least 4.5 km below sea level - Big flat part at bottom of ocean ● Seamounts: old volcanoes ● Canyons: rivers turn into sediments - Helps us find where water was at certain points ● Submarine canyons: relatively narrow and deep valleys, down cut into continental shelves and slopes ● Bathymetry: variation in depth of the ocean 10. What are the salinity patterns in the ocean (both surface and deep)? ● Salinity: concentration of salt in water - Depends on ocean temperature and location ● Ocean salinity averages 3.5%, measurements from around the world demonstrate that salinity varies with location, ranging from about 1.0% to about 4.1% ● Salinity reflects the balance between the addition of freshwater by rivers or rain and the removal of freshwater by evaporation, for when seawater evaporates, salt stays behind’ salinity also depends on water temperature, for warmer water can hold more salt in solution than can cold water ● The correlation of average temperature with latitude exists because the intensity of solar radiation varies with latitude ● Waters warmed by the sun are less dense and tend to remain at the surface 11. What are the types and underlying causes of ocean currents? ● Currents: flowing water in a defined area ● Surface currents: driven by wind and affected by Coriolis effect ● Deep currents: downwelling - Upwelling - Caused by: density (thermohaline circulation), temperature, salinity ● Currents: flows or circulates at velocities of up to several kilometers per hour in fairly well-defined streams ● Circulation is the sea occurs at two levels: - Surface currents affect the upper hundred meters or water. Occur in all the world’s oceans o They result from interaction between the sea surface and the wind – as the moving air molecules shear across the surface of the water, the friction between air and water drags the water along with it o Coriolis effect: phenomenon that causes surface currents in the northern hemisphere to veer toward the right and surface currents in the southern hemisphere to veer toward the left of the average wind direction o Gyre: surface currents make a complete loop because of the Coriolis effect - Deep currents keep the remainder of the water column in motion - Downwelling zones: surface water sinks and exchanges with deep water - Upwelling zones: deeper water rises and exchanges with surface water - Thermohaline circulation: the rising and sinking of water driven by such density, causes by differences in temperature and salinity 12. What causes tides? ● Tide: the generally twice daily rise and fall of sea level ● Tides develop in response to the TIDE GENERATING FORCE, which in simple terms is due in part to the gravitational attraction of the sun and moon, and in part to centrifugal force produced by the revolution of the Earth-moon system around its center of mass - Generates two tidal bulges in the oceans on opposite sides of our planet ● Tidal flat - High tide: covered by water - Low tide: exposed ● Tidal bulge: is larger on side closer to the moon - Smaller bulge because earth is pulled away from water on that side ● Tidal reach: elevation difference between high and low tide 13. Know the different types of waves and wave actions that we covered. ● Breaker: friction between wave and ocean floor ● Wave refraction: waves come in at angle, pushes sand up beach slightly at an angle and gravity pulls it straight back ● Open ocean waves: energy moves forward and water stays put ● Wind-driven waves develop because of the shear between the molecules of air in the wind and the molecules of water at the surface of the sea ● Longshore current: the flow of water parallel to the shore just off a coast because of the diagonal movement of waves toward the shore 14. What are the different kinds of coastlines and why do they form where they do? ● Coastal landforms: - Beach: some grow and others are being eroded - Beaches: barrier island - Sand islands - Always changing ● Rocky coast - Embayments - Headlands: stick out – eroding because they are hit by waves (creates sand) - Always changing ● Fjords: - Glacial valley - Flood after glacier melts ● Coastal wetlands: - Shallow water, no wave action - Temperate climate: salt marshes - Subtropical climate: mangrove swamp ● Coral reefs - Shallow, warm - Grows until conditions change - Erodes into coral sand ● Estuaries - Ocean rises into river valley - Mix of salty and fresh water ● What determines what type of coast? - Tectonic setting - Sea level - Sediment supply - Climate 15. What do humans do to try and stabilize the coastline? ● 44% of world population lives <150 km from coast ● 55% in US ● Coast always changing ● Sea level rise ● Groin: barrier built to keep sand from eroding and keeps neighbors from getting new sand ● Beach erosion (how to stop it) ● Jetty: protect harbor entrance - Problem is that sand goes somewhere so it makes a sandbar ● Breakwater: decreases wave energy (a wall) ● Riprap: a decrease wave energy - Anything you have that’s hard to take away the pounding of waves instead of the beach doing it ● Beach nourishment: bring in new sand 16. What hazards are associated with living near the ocean? ● Pollution and Destruction - Biggest effect on wetlands and coral reefs - Water chemistry changes - Sediment amounts - Construction ● Natural destruction - Large and small storms cause damage in several ways o Winds o Waves: removal of dunes, wetlands, beaches o Storm surge: affected by tide, wind, air pressure o Waves and surge o Flooding o EX: Katrina 17. What are the characteristics of a good aquifer? ● ● ● ● ● Aquifer: allows water to flow: high porosity and high permeability Porosity: percentage of pore space in a rock Permeability: ease of flow between pores Size, number, shape conduits Gravel is very permeable Aquitard: retards water flow (low porosity and low permeability) Water table: area underground in which pore spaces are filled with water instead of air (the line between pore spaces filled with air and filled with water) - Follows land surface ● Perched water table: won’t want to drill to a perched water table and stop because water is not being replenished and you’ll run out 18. How does groundwater move, and how is movement affected by different sediments and rocks? ● Groundwater: rain water that sinks into ground - Water trapped in rock during formation - Months to thousands of years (can stay under ground) - Water is in sedimentary rocks, solid rocks, spaces in sediment ● Depends on where you are: - If you’re un unsaturated zone, pore spaces filled with air, then it’s just gravity that moves it - In saturated zone, all pore spaces filled with water, then its pressure that moves it - Movement: moves from areas with high pressure to low pressure - Ground water moves in arcs ● All groundwater moves slowly but at different rates, why? - Darcy’s law: more permeable = faster - Steep slope = faster 19. How do humans access groundwater? ● Wells - Ordinary wells - Seasonal wells ● How does water get to your house? - Gravity driven pressure: water tower built up high, then pump up water from well to tank and then pressure pumps water from tower to houses and farther away you live from tower the less water pressure - Artesian well: works like a water tower (up above) except it is a natural process o Natural wells on earth’s surface - Spring: a place where groundwater naturally flows to the surface - Hot spring: hot water comes to surface o Two main ways: o Very deep groundwater forced up by pressure or pathway o Geothermal regions: magma near the earth’s surface 20. What are the components of a geyser? ● Geyser: water under pressure coming up ● 3 components: - Water supply - Heat source - Pluming system 21. How can groundwater resources be depleted? ● Humans can deplete the groundwater supplies ● Lowering the water table permanently: pumping water faster than it would happen naturally ● Saline intrusion: build a well and pump up freshwater faster, then the saltwater instead of fresh ● Reverse flow: change in local pressure, can change water flow - EX: septic tank flowing into water supply because of irrigation ● Land subsidence: pump water away from pores and turns into air then it can collapse 22. What factors influence groundwater quality? ● Most is safe to drink ● “soft” water – salt - Feeling of when you wash out shampoo and it feels like you can’t rinse it all out ● “hard” water – calcium, magnesium - Full of minerals and can deposit in your pipes ● Hydrogen sulfide: rotten egg smell ● Iron-rich: red/orange staining in sink ● Contamination: - Septic tanks: can leak and cause E.coli - Farm runoff: fertilizers and pesticides - Mine runoff: acidic waste from mines - Storage tanks: if it cracks, gas leaks - Industrial (small too): drycleaners biggest contamination - Landfill: garbage and rain leaks into groundwater EX: batteries 23. What geologic features are created by groundwater and how do they form? ● Caves: created by groundwater - Limestone in acidic groundwater - Water table lowers (dry caves) - Cave collapses - Caves form under water table ● Speleothems: - Calcium filled water - Evaporates and deposits calcite - Grows about 1-2 mm/year ● Stalactite: - Not hollow - Water drips off end - Grows like icicle - Grows down from roof of cave - Starts off as soda straw ● Stalagmites - Mound of floor of cave - Grows up - Water drips from stalactite makes these ● Karst landscape: landscape created by the fact that there are a lot of caves built underneath ground or caves used to exist in area and have collapsed ● Sinkholes: cave collapse ● Disappearing stream: happens in karst areas and it just goes underground 24. What are the five types of deserts and why do they form where they do? ● Desert: dry region that has: - No permanent streams - <15% surface vegetation coverage - < 25 cm rain/year - Can be hot or cold ● 5 types of deserts: - 1). Subtropical: global air circulation - 2). Rain shadow: air picks up moisture, rising air cools; rain clouds form; dry air (rain shadow) - 3). Coastal: ocean currents (cold) and wind blows it across desert and sucks up all of the moisture as it crosses the desert because its’ so dry - 4). Continental interior: far from ocean and air moisture used over continent - 5). Polar: global air circulation, cold air is dry and no moisture 25. What are the main causes of desert weathering and erosion? ● Desert weathering: - Just like physical wreathing - EX: wedging - Abrasion - Jointing ● Chemical weathering: - Desert varnish: microbial action on clay ● Water erosion (water is the largest agent in erosion) - Flash floods - High competency and capacity - High turbulence ● Wind erosion: - Wind is a fluid-erodes like water - Energy level determines grain size 26. How is sediment transported and deposited in the desert? ● 5 types: ● Alluvial fan: - Abrupt change in velocity - Stream dumps coarse sediment ● Talus Apron: - Pile of debris - Caused by gravity ● Salt lake - No outlet - Water collects and evaporates - Salt concentrates ● Playa - Dry lake bed ● Dunes: - Wind moves sand - Wind carries small grains away - Larger grains only move so far - Types of dunes: amount of sand and wind direction and speed 27. What kinds of geological formation and landscapes are associated with deserts? ● Chimney, mesa, butte (basically all the same just different sizes) ● Formation of desert landscapes: - Mass wasting - Weathering - Erosion ● Desert pavement: natural stone mosaic with soil underneath - These stones occur and then dust and soil accumulates beneath stone and stones crack then desert varnish coat rock and smaller stones fit together like pavement ● Soil Crust: - Organisms on surface - Can’t have a desert without it 28. How is desertification caused? ● Desertification: changing non-deserts to deserts ● Causes: - Deforestation - Overgrazing - Agricultures - Water mismanagement - Drought (natural) 29. What are the types of glaciers, how do they form, and how do they move? ● Glaciers: made of ice, move slowly, and basically a river made of ice ● Formation of glaciers: - Large amount of snow - Most does not melt - Gentle slope (have to have one) - Stratified - Compact over time - Snowflakes on top actually look like snowflakes but the bottom is crystals of ice because of pressure ● Glacier ice: water absorbs non-blue light wavelengths - Less air after compaction - Looks super blue which is old ice ● Types of glaciers: - Mountain - Continental - Temperate - Polar - Can mix these together like mountain-temperate ● Mountain glaciers: 4 types - Ice cap: top of mountain - Valley glacier: glacier in a valley - Cirque: fills low places, trapped/doesn’t move out - Piedmont glacier: valley glacier spreads out into plain and gets flat 30. What causes glacier advance and retreat? ● Gravity is prime mover ● Each glacier moves at different rates ● Two main types: - Basal sliding: slides on melt and slides down on water - Plastic deformation: solid changing shape, occurs below 60m, ice cracks above 60 m ● Glaciers always move downslope and or out from center ● ALSO, advance and retreat ● Retreating: glaciers get smaller overall ● Advancing: glacier gets overall larger in volume ● Causes: - Amount of snow - Summer temperatures ● Icebergs: - Calving (falling off) into ocean - When glacier gets to its’ end (water) 31. How do glaciers erode and deposit sediment and what landforms do they create? ● Glaciers are huge eroders ● Do it by: - Incorporation (get rocks and pluck them) - Plucking - Bulldozing ● Embedding rocks - Striations - Polishing - Dust ● Erosional landforms: - Arête: ridge caused by 2 glaciers. French for “knife” because its pointy - Horn: peak shaped by 3 glaciers, looks like pyramid - U-shaped valley: formed by glacier - Hanging valley: valley that abruptly ends - Fjord: coastal valleys filled with water. Sea level changes. Straight up and down sides of u-shaped valley just with water ● Glacial deposition: - Moraine (is a till): o Pile of sediment o Lateral (on side of glacier) o Medial (middle of glacier) o - Till End (end of glacier) o Sediment dropped by glacier o Unsorted - Ervatics o Large, random debris o When glacier melts it drops all sediment right there - Glacial marine: o Iceberg deposits - Glacial outwash o Sorted o Glacier ending and melting and is taking away the till and is being sorted - Loess: windblown clay ● Depositional landforms - Reworked moraine and till - Ervatics - Kettle hole (giant hole) 32. What global consequences result from glaciers? ● Ice loading and glacial rebound - Isostasy: ice on top causes earth to push down and another part of the earth to pop up ● Sea level change - Global 33. How do geologists know about the history of glaciation events? ● How do we know this? - Giant piles of sediment - Till deposits ( dropped at end of glacier) - Late Paleozoic: plate tectonic evidence - Small frequency events - Most recent = Pleistocene Ice age o Ended 11,000 years ago o Huge continental glaciers o Till deposits o Pollen o Fossils 34. Why is New Orleans sinking? (covered in multiple classes) ● Isostasy: ice on top causes earth to push down and another part of the earth to pop up - Lithosphere maintaining equilibrium ● Glacier in Michigan is melting to New Orleans is sinking now ● Human activity: - Wetland removal - Nowhere for water to go ● Artificial levees: - No new sediment ● Extracting groundwater - Compacting sediment