Geog 101 Exam 2 Study Guide
Geog 101 Exam 2 Study Guide GEOG 101 002
Minnesota State University, Mankato
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GEOG 101 002
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GEOG 101 002
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This 8 page Study Guide was uploaded by Hallie Notetaker on Sunday October 9, 2016. The Study Guide belongs to GEOG 101 002 at Minnesota State University - Mankato taught by Phillip Larson in Winter 2016. Since its upload, it has received 315 views. For similar materials see Physical Geography in Geography at Minnesota State University - Mankato.
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Date Created: 10/09/16
GEOG 101 Exam 2 Study Guide Topic: Living with Earth’s Remodeling (volcanoes and diastrophism) Definitions: Basalt lava flow – travel great distances and slope angles will reflect low viscosity; not explosive Rhyolite lava flow – small eruptions; so viscous that is has trouble flowing and piles up in dome shape Pahoehoe –smooth undulating or ropy masses A’a – very rough jagged masses with a light frothy texture Caldera – from callapse after lava has “evacuated” from magma chamber Crater – depression at top formed by force of eruption Sill – horizontal magma inserted between Dike – over time, less resistant rock comprising the flank of the volcano is eroded away leaving the resistant dikes exposed Fault escarpment – a steep slope or long cliff that forms as an effect of faulting or erosion and separates two relatively level areas of differing elevations Key Concepts/Questions: What type of volcanoes are associated with basaltic lava? - Shield and cinder cone volcanoes Know the difference between the different types of volcanoes (difference in height, steepness of slopes, etc.) - Cinder cone – drops out like hour glass - Shield – broad, domed volcano with gently sloping sides - Composite – alternating pyroclastic layers and lava flows; intermediate in steepness; intermittent eruptions over long time span; sit over subduction zones; very dangerous Know what types of lava are most viscous and least viscous - Basalt – low viscosity - Andesite – intermediate viscosity - Rhyolite – high viscosity Why is viscosity important in determining the violence of a volcanic eruption? - The more viscous the lava is, the more explosive Where would you expect to see a lot of pyroclastics? On a lava flow, shield volcano or composite volcano? - Composite volcano What does the Columbia Plateau in the Pacific Northwest, the traps in Siberia and the Deccan traps in India all have in common? - Flood basalts How are lava tubes made? - Formed by lava which moves beneath the hardened surface of a lava flow - Tubes can be actively draining lava from a volcano during an eruption, or can be extinct, meaning the lava flow has ceased and the rock has cooled and left a long, cave-like channel What type of volcano and plate boundary are associated with andesitic lava? - Composite volcanoes and subduction zones (convergent) The hazards associated with a composite volcano - Intermittent eruptions over long time span - Tephra – blasts composed of lava fragments and gas that are erupted into the air - Pyroclastic flow – high-speed avalanches of hot rock, gas and ash that are formed by the collapse of lava domes or eruption columns (lethal, burning, burying or asphyxiating in their paths) - Volcanic ash – made up of tiny jagged particles of rock and glass - Debris avalanches – rapid landslides of rock, soil and overlying vegetation, snow or ice - Lahars – fast moving slurries of rock, mud and water that move down river valleys What is the difference between a nuee ardente and a lahar? Which one poses the greatest danger to populations living around composite volcanoes? - Nuee ardente – an incandescent cloud of gas, ash and lava fragments ejected from a volcano, typically as part of a pyroclastic flow - Lahars – fast moving slurries of rock, mud and water that move down river valleys - Lahars pose the greatest danger for people living around composite volcanoes Why do rhyolite eruptions tend to produce large calderas? - Rhyolite flows are highly explosive When rhyolite eruptions do not produce calderas, they make rhyolite domes. Why are rhyolite domes so steep sided? - The lava has trouble flowing since it is so viscous so it piles up in a dome shape From largest to smallest what are the intrusive igneous deposits? (dike, batholith, plutons, laccolith) - Dike, plutons, batholiths, laccoliths What intrusive igneous deposit would you expect to see at the core of a big mountain range? - Batholiths What intrusive igneous deposit would you expect to see at the core of a single mountain such as the Henry Mountains on the Colorado Plateau? - Laccoliths Why do you see dikes as long linear ridges sticking out of a landscape made up of sedimentary rocks? - Over time, less resistant rock comprising the flank of the volcano is eroded away leaving the resistant neck and dikes exposed Would you expect to see a pluton coming out of a dike? Why or why not? - No because plutons are further below the ground than dikes Know which fault type goes with what type of stress and the places they might occur - Normal = extension – Basin and Range, Death Valley - Thrust = compression – Pacific Northwest, Mexico - Transform = side-by-side – central California, Turkey and Levant Where in the United States would you expect to see evidence of normal faulting? Strike-slip faulting? - Normal fault – Basin and Range Province (eastern California, most of Nevada, Western Utah - Strike-slip fault – San Francisco What type of faulting would be associated with triangular facets and wineglass valleys? - Normal faulting What is the difference between horsts and grabens and what type of faulting produces them? - Horsts and grabens are a result of normal faulting; horsts are high and grabens are low; they always form together in alternating sequence What do San Francisco, Hayward, Los Angeles and Palm Springs have in common? - They all lie along the San Andreas Fault What type of faulting produces offset drainages, beheading of streams and sag ponds? Why? - Strike-slip faulting because they always fault at right angles causing whatever is on top of them to shift Does faulting always have to occur on a major fault zone? What famous earthquakes occurred on places where nobody had identified a fault previously? Does strike-slip faulting occur only in California? Where else? - Turkey and Levant What is a tsunami and how are they related to faulting hazards? - A long, high, repeating sea wave caused by an earthquake, submarine landslide or other disturbance Topic: Weathering Definitions: Dolines – (sinkhole) a depression or hole in the ground caused by some form of collapse of the surface layer Speleotherms – a structure formed in a cave by the deposition of minerals from water; e.g. stalactite or stalagmite Key Concepts/Questions: What is the weathering process that produces sinkholes? What is the term for landscapes that are dominated by this weathering process? - The weathering of karst landscapes with subterranean drainage - Karst topography Granite experiences chemical weathering from hydrolysis, hydration, oxidation and chelation. What evidence of this weathering would you expect to see in the natural landscape? - Evidence of granite sand called GRUS - Core stone piles of tors that are left behind when GRUS washes away with rain - Spheroidal forms that were exposed with the erosion of GRUS The jagged appearance of alpine scenery is usually attributed to what process? - Frost weathering How does jointing (or joint density) influence weathering? - Jointing creates fractures that allow water to penetrate and weather the rock Physical weathering processes - Frost weathering - Pressure release weathering - Salt weathering - Thermal expansion/contraction - Wedging - Wetting/drying - Root pressure In a desert landscape, what general process limits the speed of landscape degradation? - The lack of vegetation where the rate of weathering limits the rate of transport What is faster in deserts, the rate of weathering or the rate of transportation of weathered particles? What rock is a reddish coloration associated with? - Oxidation What are karst landscapes produced by? - The dissolution of soluble rocks such as limestone, dolomite and gypsum Identify the following as either chemical weathering or mechanical weathering - Frost weathering – physical - Pressure release – physical - Salt weathering – physical - Dissolution – chemical - Hydrolysis – chemical - Hydration – chemical - Thermal weathering – physical - Wetting and dehydration – physical - Root pressure – physical - Oxidation – chemical - Chelation – chemical What is a common rock that can be dissolved easily by water and weak acids? - Limestone Which state would most likely have the highest ratio of physical weathering to chemical weathering rates? - Physical weathering occurs in areas with lower temperature and precipitation - Northern part of the country Why would wind not create delicate weathering features like alveoli tafoni? - Wind smooths rocks while weathering roughens rocks When wedging by soil wetting/drying and calcrete growth opens up a rock fissure, what is the visual clue? - Cracks in bedrock, mountain sides or giant boulders In which setting is karst topography most likely to feature steep pillars, knobs and oddly shaped rocks? - Tropical What is the main reason oceans are salty? - Salt in the ocean comes from rocks on land How does physical weathering aid chemical weathering? - The physical breaks the rocks down and creates more pathways for water to come in and dissolve the rock How does air pollution accelerate dissolution of stone monuments? - Iron oxide What happens to the surface area of exposed rock if a rock is fractured? - The surface area increases as the rock is fractured What is left in the water after limestone dissolves? - Calcium deposits Why does granitic rock break into parallel sheets? - Granitic rock has planar joints What are joints? How do they form in a lava flow? - Fractures that allow water to penetrate and weather the rock - Columnar jointing – from contraction after lava flow cools or faulting/folding stresses the rock What are the visual clues that a rock has been weathered by salt weathering? - Crystallization exerts pressure - Heating and cooling exerts pressure What do aluminum cans, plant nutrients, beach sand, dark streaks on cliff faces and the mud that sticks to your shoes all have in common? - Aluminum and iron oxides In a forest or grass-covered landscape, what general process limits the speed of landscape degradation? - Vegetation cover where the rate of transport limits the rate of erosion What is faster in forests, the rate of weathering or the rate of transportation of weathered particles? Which state would most likely have the highest rate of chemical weathering? - Chemical weathering occurs in areas with higher temperature and precipitation - South/Southeastern part of the country What type of valleys would you expect to find in a karst landscape? - Sinkholes Topic: Understanding Soils Definitions: Soil texture – relative proportions of sand, silt and clay in a soil; soils with the finest texture are called clay soils while soils with the coarsest texture are called sands Soil degradation – the decline in soil quality caused by its improper use, usually for agricultural, pastural, industrial or urban purposes; a serious global environmental problem and may be exacerbated by climate change Salinization – build of salts in the root zones of plants; common in arid regions and semi-arid areas with intensive agricultural practices Desertification – the process where fertile land becomes desert typically as a result of drought, deforestation or inappropriate agriculture Eluviation – downward movement from an upper soil horizon Illuviation – the deposition of colloids, soluble salts and suspended mineral particles in a lower soil horizon Laterization – found in tropical areas, lots of weathering and leaching; very poor nutrients in the soil; typical resulting soil type is oxisols Spodosols – ashy-grey acidic soils with a strongly leached upper layer; produced by podsolization Key Concepts/Questions: What type of soil would you expect to find in desert and semi-arid areas? What would it look like and why? - Aridisol - Surface layer may be a desert pavement - Dry-low humus What horizon contains the primary sources of nutrients for plants? - A horizon What is the primary difference between the O and A horizons? - O horizon – surface accumulation of organic debris; may not be present; e.g. fallen leaves - A horizon – mineral horizon that contains humus; top soil The different soil horizons and their correct order - O Horizon (fallen leaves) – surface accumulation of organic debris; may not be present; immediate surface layer in which organic material, both fresh and decaying, predominates - A Horizon (top soil) – mineral horizon that also contains considerable organic matter; usually dark in color; location of germination of seeds; an eluvial layer from which minerals have been removed; contains humus - B Horizon (Higher mineral and lower organic content) – mineral horizon of illuviation where minerals removed from above have collected; brown to red color due high clay and/or iron oxide content - C Horizon (gravel and rocks) – unconsolidated parent material, beyond the reach of plant roots; lacking in organic matter; commonly referred to as regolith - Bedrock – unweathered rock; parent rock What factors influence the development of soils? - Climate – temperature (determines chemical reaction) - Organic activity, type of vegetation, soil bacteria - Relief – top, slope, base - Parent material – limestone, granite, sandstone or dust - Time – increases horizonation; leaches nutrients; can take 10,000 years to produce significant B horizons What type of soil would you expect to find in tropical areas? What would it look like and why? - Oxisols - Contain few weatherable minerals and are often rich in iron and aluminum oxide materials What distinguishes dirt from soil? - Soil has more nutrients What type of soil would you expect to find in conifer forest areas? What would it look like and why? - Spodosols - Ashy-grey, acidic soils with a strongly leached upper layer What is soil primarily composed of? - Minerals, organic matter and water The CLORPT models suggest soil development is controlled by what? - Climate, organic activity, relief, parent material and time What occurs in waterlogged soils? What soil type does it produce? - Gleization - Produces histosol What two types of soil do not show or weakly show horizonation (soil profile development)? - Entisols and inceptisols Topic: Mass Wasting Definitions: Sorting – the process where sedimentary particles become separated Slides – translational when the failure occurs on a flat plane and rotational slump when the failure occurs on curved surface Earthflow – slower and thicker Debris flow – more rocks mixed with mud Mudflow – few rocks Mass wasting – the downslope movement of slope material Key Concepts/Questions: What do debris flows leave that create ridges along the side of the path it flows down? Falls, topples and slides are examples of what? - Mass wasting How can sorting be used to distinguish a debris flow deposit from a deposit from a stream or river? What process turns solid material into a more “plastic” material, allowing it to be malleable and flow? - Thixotropic When the rock fall is a rotating slab, what is it called? - Topple The key factor in all mass wasting events - Gravity Before a rock on cliff can fall, what must happen first? - Detachment from a steep slope or undercutting What factors contribute to a mass wasting event? - Increased slope steepness, increased water, decreased vegetation, earthquakes Rock debris deposited at the base of a cliff or hillslope is called? When the pile has a conical shape it is called? - Talus - Talus cone Why do fires often lead to debris flows? - Fires destroy the top layer of soil resulting in a lower root resistance to precipitation that then causes debris flow True or False: Landslide, rockfalls, and other mass wasting events are only dangerous in places that have mountains (like Colorado or California), but are not something to worry about in other places (like Minnesota). - True they are highly dangerous in those areas, but still possible in areas like Minnesota The angle of a slope reflects the equilibrium between what two things versus resistance to transport (friction)? When an earth material (rock or sediment) is easy to transport the slope of that material will likely be what? Steep or flat? - Steep When an earth material (rock or sediment) is difficult form natural processes to erode and transport, the slope will likely be what? Steep or flat? - Flat How does sediment deposited from mass wasting events differ from that transported by rivers?
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