Geography 1 Final

What factors contribute to the danger posed by earthflows, debris flows, and mudflows?

- An earthflow (earth flow) is a downslope viscous flow of fine-grained materials that have been saturated with water, and moves under the pull of gravity. They are an intermediate type of mass wasting that is between downhill creep and mudflow. - A DEBRIS FLOW (commonly called a MUDSLIDE by the media) is a moving mass of loose mud, sand, soil, rock, water and air that travels down a slope under the influence of gravity. - Mudflow=a fluid or hardened stream or avalanche of mud.

Explain the formation and accumulation of clays in soils.

- Formation: minerals get broken down, smallest particle size, most surface area, best for plants - Clay usually accumulates in B horizons. They are most common for leaching and are removed from the A horizon to lower horizons, so there isnt usually a lot of clay in A horizons.

Explain the various services provided to humans by soils

- Grow food - Receive nutrients (phosphorous, nitrogen, carbon) - The surface upon which we build

Explain liquefaction, where it occurs, and the threat it poses in earthquake-prone areas.

- Liquefaction is a phenomenon in which the strength and stiffness of a soil is reduced by earthquake shaking or other rapid loading. Liquefaction and related phenomena have been responsible for tremendous amounts of damage in historical earthquakes around the world. - Liquefaction occurs in saturated soils, that is, soils in which the space between individual particles is completely filled with water. This water exerts a pressure on the soil particles that influences how tightly the particles themselves are pressed together. Prior to an earthquake, the water pressure is relatively low. - However, earthquake shaking can cause the water pressure to increase to the point where the soil particles can readily move with respect to each other. - When liquefaction occurs, the strength of the soil decreases and, the ability of a soil deposit to support foundations for buildings and bridges is reduced

How do differences in parent materials influence soil depth or properties?

- Soil forms directly from residual parent material in the bedrock. More resistant bedrock leads to shallow soil this impacts what can grow there - Depending on the properties of the parents material soil can be high or low in nutrients --distinctive color --shallow depending on how easily parent material is weathered --presence of certain elements like iron --how much water the soil can absorb

Explain the difference between soil, regolith, and bedrock

- Soil: dark, brown material, upper layer of earth, made up of organic material, clay, rock materials - Regolith: layer of loose rock, dust, sand and soil resting on the bedrock that constitutes the surface layer - Bedrock: the solid rock that exists at some depth below the surface, it has not been transported from another location

Explain different types of drainage basins for channels (e.g. rivulets, streams, rivers) of different sizes.

- Trellised: develop where there is strong structural control, channels align themselves parallel to structures in bedrock - rectangular: areas with tectonic faults or bedrock joints - parallel: found in areas with steep relief with no cohesive material - dendritic: on erodable sediment and dipping bedrock - deranged: areas recently disturbed by glacial acitivity or volcanic deposition, it will adjust by transporting sediment to improve flow

How do soils from wet, temperate, and dry climates differ from one another?

- Tropical/wet = thin or absent humus, thick masses of insoluble iron and aluminum oxides; iron rich clays, thin leached zones, mafic igneous bedrock - Dry = humus and leached soil calcium carbonate, sandstone, shale, limestone bedrock - Temperate= humus and leached soil, some iron and aluminium, all carbonates leached away, granite bedrock

Explain why deltas are so dynamic. Explain why sediments deposited in a delta are typically different sizes depending on how far from the mouth of the river they were deposited.

- a landform that forms from deposition of sediment carried by a river as the flow leaves its mouth and enters slower moving standing water - sediment is constantly being brought in and changing the structure of the land - Sediment accumulates in different parts at different rates depending on elevation, hydrodynamics of river and tide, configuration of channels, vegetation structure - finer sediment is lighter and can be transported farther - coarser sand and gravel are usually transported as a bedload and are the first to drop out and accumulate thus the grain size closer to the opening of the river is larger and coarser and get finer the farther you move away

Explain other problems associated with human exploitation of groundwater.

- as we pull out groundwater we often pollute it - it is not unlimited - it causes the ground to sink as we pull out water - it has bad erosion effects and lowers the water table

Explain the concept of base level. Why does it matter?

- base level of a river or a stream= the level below which the stream cannot erode its bed. at this lowest level the water of the stream has less velocity (like the bottom of a slide) which means the water flow has less energy so the ability to erode or chip away at the land decreases - this is important because based on the energy/ velocity of the water shows the way in which it shapes the ground around it

Explain how different landforms give rise to different drainage patterns.

- depending on the type of surface the water will cut into it differently - some landforms are sloped and cause the drainage patterns to move about circularly - some landscapes are hard and rivers erode into tectonic cracks and are angular

What causes some fluvial valleys to have a v-shape while others are are shaped like canyons?

- downcutting and mass wasting - some are V shaped because the material they are cutting into is soft and collapses as they cut in turning it into cliffs - some look like canyons because they down cut into hard material that holds its shape - Mass Wasting: slope movement, when soil and rock move downslope as a mass, largely by the effect of gravity

Explain the concept of drainage basins

- drainage basin: big physical boundary that funnels out water, it includes water table water and surface run off, rain and snow melt gather there and flow to a body of water , they contain stream that funnel out the water

What causes seasonal variations in groundwater table height? Why does the groundwater table follow, in a muted way, the topographic surface?

- during the dry season no water is added, during wet season water is recharged - groundwater table follows the topographic surface

Explain the concepts of wilting point, field capacity, gravitational water, hygroscopic water, and capillary water.

- field capacity: amount of soil moisture or water held in the soil after excess has drained away and the downward movement has decreased - wilting point: occurs when the water content is too low for the plant to remove water from the soil, not dry, water is just not accessible - gravitational water: water that moves rapidly out of well drained soil due to gravity, not available to plants - hygroscopic water: absorbed from the atmosphere and held very tightly by soil particles so it is not available to plants - capillary water: water that remains in the soil after gravitational water is drained out, is in the form of a fim around the soil grains

What influences groundwater quality? What is water hardness?

- groundwater quality= it can be contaminated by landfills or gas stations leaking toxins into the water table - water hardness= the most common water quality concern. when it is high in dissolved minerals, specifically calcium and magnesium, the water becomes 'harder'

Explain the importance of undercutting in headward erosion and river widening

- headward erosion (at the origin of a stream) where it erodes at its source, seemingly lengthening its channel in a direction opposite to that flow - as headword erosion is occuring it can begin to undercut the cut behind it since the area behind it is usually steeper and thus it undercuts making these sorts of formations

What creates hotsprings and geysers?

- hot springs: groundwater is heated by magma that is close to the surface, and then comes through a rock fissure - geysers: magma rises at a hot spot and heats the aquifers which comes to the surfaces through a rock fissure

Explain why rivers erode into their headwaters, a process called headward erosion. How does headward erosion enable stream capture?

- in headward erosion the stream erodes away at rock and soil at its source in the opposite direction. as the original stream gets closer to a body of water, it flattens out, which increases erosion at the source - if headwater erosion goes on for long enough, it can break through into a watershed and capture drainage that previously flowed to another stream

Explain the concepts of infiltration, percolation, groundwater flow, overland flow, runoff, infiltration excess

- infiltration: water on the ground enters the soil, rate at which soil is able to absorb rainfall, this rate decreases as soil becomes saturdated, movement of water into the soil surface - percolation: movement of water WITHIN the soil matrix, the percolation rate controls the infiltration rate, due to gravity. the rate of percolation is controlled by grain size - groundwater flow: part of streamflow that has infiltrated the ground - overland flow: movement of water over the land, downslope toward a surface water body - runoff: flow of water when excessive storm saturates soil and causes it to run over the surface - infiltration excess: when water enters soil faster than it can be absorbed, the water is not saturated but it cannot absorb quickly enough so there is still excessive run off

Explain how permanent water bodies are related to the groundwater table.

- most bodies of water appear where the earth drops below the water table, thus as the water table drops so will these bodies of water - springs and groundwater discharge allow streams and lakes to forms

Where would you find an entrenched meander?

- occurs when a stream is forced to start downcutting by uplifting, or a drop in the base level - the grand canyon and other spectacular canyons are characterized by entrenched meanders

Explain the motion of water in an open water wave. How does this relate to surface waves in earthquakes?

- out in the ocean, waves move around in circles, pushed by the wind - longer wavelengths out in the ocean - a tsunami is when you get a push under the ocean to move water - water moves in a circular motion as wave passes the lower limit of wave induced limit is the wave base as wave moves toward the shore, water gets shallower than wave base, which causes erosion. It moves from circular to elliptical motion in shallow water - Crests become narrower than the troughs, forward velocity decreases to the point that the crest moves faster than the water underneath Relates to surface love and raleigh waves due to its circular motion

What differentiates the different types of aquifers (perched, unconfined, confined)?

- perched: separate water table, at higher elevations than the main water table - unconfined: the water table is its upper boundary, very near the ground - confined: the aquifer is being held under pressure between two confining layers

Explain the differences between porosity and permeability? How does each influence the size or accessibility of an aquifer? How do variations in rocks determine each?

- porosity: measure of how much of a rock is open space, storage is controlled - permeability: measure of the ease with which water can move through porous rock, flow is controlled by permeability. usually increased permeability goes with increased porosity - constant permeability accompanied by increased porosity indicates the presence of more numerous, but smaller pores - Porosity controls the size of an aquifer because it controls how much water can be absorbed - permeability controls how accessible that aquifer is and how much water reaches it - variations in rocks: sand grains allow alot of pore space, but when they are cemented they are not permeable, fine grained sand stone has less spaces than sandstone with irregular shapes

Explain the concepts of recharge and discharge? Where does each occur? How do they relate to groundwater flow?

- recharge of groundwater: natural process of infiltration and percolation of rainwater from land or stream into permeable soil that store water, groundwater flow would decrease if there was no recharging from upper soil and runoff , primary mechanism for aquifer replenishment, ensuring a future source - discharge: where the water table intersects the ground surface, involves water seeping out of streams and lakes

How do soil properties change, in general, from the equator to the pole?

- soils vary with temperature and aridity as they move from the equator. As you decrease in aridity soil becomes darker (richer in organic material); as you decrease temperature there is less and less vegetation moving up from the equator to the north pole Soil moves from - Forest Savanna Desert - Forest Grassland Scrub Desert - Forest - Tundra (at the pole)

What determines the amount of leaching that occurs in a soil? How does this relate to percolation?

- the pore space in soil determines leaching percolation: when water passes through a filter determines how many materials move down horizons - lower percolation rate means less water is leached through

How does glacial ice differ from snow? What is the process that converted snow to glacier ice called?

- the re-crystallization of partially melted snow into a granular form of ice known as firn. Over time, accumulated firn will compact, eventually resulting in the formation of dense glacial ice. Over an extended period of time a glacier will form which can grow to be thousands of feet thick. - When a glacier spreads out over water that portion is called an ice shelf. When these shelves form and extend out into the sea they become brittle and fracture. Eventually chunks of ice will break off in a process known as calving, producing icebergs.

How do the distribution of soils relate to the distribution of climate zones and biomes?

- the soil determines what vegetation can grow there, and vice versa. If soil is hard and lacking nutrients based on its bedrock then not much vegetation will grow there and this will affect the biome. In the same way if trees favor a certain side of a mountain based on sunlight their presence can change soil's chemical composition

How do temporary water bodies immediately after rain differ from permanent water bodies?

- this is just an educated guess but temporary bodies of water are most likely above the water table, forming when the soil below them is saturated and cannot obsorb anymore, eventually though gravity will pull that water down to the water table, opening up space and absorbing that temporary body of water - permanent bodies of water though form when the earth dips below the water table and so they do not disappear except for when the water table begins to dry up

How does the unsaturated zone differ from the saturated zone? How does this relate to the concept of gravitational water?

- unsaturated: immediately below the land's surface, contains both air and water - saturated: area in aquifer below the water table, in which all pores are saturated with water. the reason the saturated zone is lower down is because gravitational water is pulled down until it is unable to move anymore, such as where all the pores of the soil are full of water

How do rivers differ in their upper reaches from their lower reaches?

- upper: flow in sharp mountain valleys, the width is narrow and the quantity of water is small, the current is rapid, bigger stones - lower: width is wide with a large quantity of water, slopes are quite even and the current is slow, meandering rivers are frequent

What allows water to erode valleys?

- water dislodges and drags away rocks from the valley floor, hydraulic action - mechanical erosion of boulders pebbles and smaller sediment carried down the river, this adds to the deepening and widening process (abrasion) (corrosion) least impactful erosion, rocks are dissolved by streams

How do wells work? How does the groundwater table change around a well? What's an artesian well? What causes it? How does it relate to water pressure in your house?

- wells= drilled down pipes into water table that then pumps the water out, unless the force of the groundwater itself pushes it out, depending on the movement of the water - artesian well is when the water pumps itself out because the water table is above where the pump is creating pressure on the water below due to a slope - around a well the ground water creates a cone of depression, reduction of water table levels. the cone of depression causes a reduction of pressure

Explain the relationship between uplift and denudation

> Denudation is the long-term sum of processes that cause the wearing away of the Earth's surface by moving water, ice, wind and waves, leading to a reduction in elevation and relief of landforms and landscapes > Uplift, in geology, vertical elevation of the Earth's surface in response to natural causes. Broad, relatively slow and gentle uplift is termed warping, or epeirogeny, in contrast to the more concentrated and severe orogeny, the uplift associated with earthquakes and mountain building.

Define mass wasting. What are the factors that lead to mass wasting?

> Mass wasting is the process by which soil, sand, regolith, and rock move downslope as a mass, largely under the force of gravity, but frequently affected by water and submarine environments and mudslides. When the gravitational force acting on a slope exceeds its resisting force, mass wasting occurs. > Factors that change the potential of mass wasting include: change in slope angle, weakening of material by weathering, increased water content; changes in vegetation cover, and overloading.

What is the difference between a river's uplands, the flood plain and the stream channel?

> uplands: higher land just past flood planes, higher up from erosion by flooding river > floodplains: flat area that is prone to flooding when the river overflows, covered in sediment from river, less vegetation > Stream channel: path for water and sediment flowing within stream banks

Explain eustatic vs. relative sea level change? What gives rise to each?

>Eustatic change (as opposed to local change) results in an alteration to the global sea levels due to changes in either the volume of water in the world's oceans or net changes in the volume of the ocean basins. >Relative sea level is the sea level related to the level of the continental crust. Relative sea level changes can thus be caused by absolute changes of the sea level and/or by absolute movements of the continental crust.

Define ablation. What causes it?

Ablation = Surface removal of ice or snow from a glacier or snowfield by melting, sublimation, and/or calving.

What is a moraine? Where do they form? Are they well sorted or not, why? How do they form?

Accumulated debris, which consists of rock, glacial till and soil, will form deposits called moraines along the sides, in front and underneath. Those that form along the sides are lateral moraines. A mound of glacial debris that is pushed up at the front of a glacier is a terminal moraine. Where a glacier has over run its former terminal moraines as it continued forward, it forms recessional moraines. Where two mountain glaciers merge into one larger glacier, two of the lateral moraines will also merge forming a moraine down the center of the larger glacier called a medial moraine.

What is an angle of repose? Explain how water influences the angle of repose.

Angle of Repose - The maximum angle at which a slope of loose material will lie without cascading down slope. Water should decrease angle because it will make the loose material cascade down

How does a landslide differ from a flow?

Landslide=the sliding down of a mass of earth or rock from a mountain or cliff. Flow=more finely grained materials than rock down a slope

In which soil level does leaching or accumulation occur?

Leaching technically occurs in the A level and accumulation in the B level or zone of illuviation. The zone of illuviation starts as the C horizon of weathered and eroded parent material until organic material and nutrients is leached down from the A level creating the B level.

Explain glacial advance and retreat. What happens to the zones of accumulation/ablation during these glacial movements? What happens to the movement of the ice during these glacial movements?

Reasons for ice sheet retreating >Global warming (global scale reason) >Change in storm track, which reduces moisture supply to glacier (regional scale reason, especially for North America) >Inputs (accumulation) -- Snow (firn) >Losses (ablation) -- By melt and evaporation >Equilibrium -- Accumulation = Ablation

How do winter and summer beaches differ? Why?

Summer: beaches are really wide, sandy Winter: beaches are rocky because of increased wave activity brings the sediment out to sea

How does location (on a plateau, ridge, slope, or basin) influence soil properties and depth?

Valley=Deep layer of soil, material eroded from steep slopes trickles down. If it is not well drained, the accumulation of water optimal for the chemical processes of soil formation Hillside= thin layer of soil because water runoff and steep slopes increase erosion - The steepness of a geographical feature effects runoff which effects mositure that can penetrate lower layers of soil - Shaded slopes store more moisture in the soil than other sides, allows more leeching of nutrients, changes soil horizons - The amount of sunlight it receives affects water amounts and affects formation

What can cause base level to change?

base level changes when - climate change: glaciation and changes in rainfall - tectonic change: where land is uplifted after plate movement or volcanic activity - sea level rise or fall in relation to land a base level cannot erode below the level of another part downstream - this means that when the main river drops its base level it drops the base level of connecting smaller streams and thus interconnectedly determines large parts of the local geography

What causes longshore drift of sand? How does it relate to longshore current?

beach drift and longshore current move sediment parallel to the shoreline both bring sediment in and out of the beach (perpendicular zigzag pattern) longshore current transport sea floor sediment and carry it parallel to the shoreline rather than up onto the beach

What are some consequences of longshore drift?

estuaries, sediment coming off the land, spits

Explain the formation and flow of continental and valley glaciers

formed by compacted firn move via glacial creep or glacial sliding

Explain the ways we know about climate change on intermediate and long timescales.

glaciers melting/sea levels rising

Explain a glide plane, and how it leads to mass wasting. What determines whether something behaves as a glide plane?

glide plane = a surface which allows a slide to occur obviously it can lead to mass wasting because it lets mass slide down the slope

What's so great about loams?

loam is the ideal plant growing medium. it is a combination of equal parts clay, silt, and sand. clay and silt help retain moisture, while sand keeps the soil from over-compacting. this helps with drainage. it doesn't get dried out or water logged

What causes channelization and stream formation?

starts out as small trickle flowing down hill, picks up more water as it flows downhill, erodes earth by picking up sediment and moving it down, steadily becomes a stream

What causes Ice Ages?

tectonics global atmosphere: weathering and cO2 insolation milankovitch cycle (long term variations in the orbit of the Earth which result in changes in climate over periods hundred of thousands of years) eccentricity tilt wobble -->all sync up to sometimes cause ice age

Explain stream meander and oxbow lake formation

the velocity and energy of the water is most at the edges so as it hits the curves it cuts into the bend while soil is deposited on the other side, this causes the river to meander more and more. Eventually it bows in so much it connects and the river takes to this path of least resistance dropping sediment on the other side and disconnecting the ox bow lake

How does wave action influence coastlines? What is a wavecut bench?

wave action flattens out the coast over time by depositing sediment

What causes waves to break? What causes them to refract? Why?

wave break = water in the wave crest breaks down and surges toward the beach bending of waves from the headlands = refraction

What is an atoll and what two processes are responsible for making them?

at hot spots when the volcano pushes up through the ocean surface, pushes up to a certain elevation than starts to erode in the shallow parts of the island - around it, coral reefs begin to form, surround these places eventually all the land erodes back into the sea and all is left is the reef

Explain the forces that give rise to creep. How does creep relate to longshore drift?

Downhill creep, also known as soil creep or commonly just creep, is the slow downward progression of rock and soil down a low grade slope; it can also refer to slow deformation of such materials as a result of prolonged pressure and stress. Creep and longshore drift are both involved in moving sediment and erosion

What influence do hurricanes exert over coastal systems?

Hurricanes pushes a wall of water out in front of it, creating flooding

What is the basic timescale for soil formation?

From 45 years in warmer climates to more than 3000 in cold climates

How fast do different mass wasting processes occur? What factors control the speed of the processes?

Mass wasting may occur at a very slow rate, particularly in areas that are very dry or those areas that receive sufficient rainfall such that vegetation has stabilized the surface. It may also occur at very high speed, such as in rock slides or landslides, with disastrous consequences, both immediate and delayed, e.g., resulting from the formation of landslide dams.

What are the basic soil horizons?

O- organic material in various stages of decomposition A- lies at the top (darkened by organic material) B- middle, often receiving dissolved and suspended particles from above, C- lies at the bottom, where the weathering has occurred and is mostly just the original parent material

How does a slump differ from a flow?

slumping moves up or flat, flow is moving down

What gives rise to tides of different sizes on the Earth? How do they relate to the phases of the moon?

The spring tides: you get constructive interference (full/new moon) king tides - earth is closest to the sun neap tides - deconstructive interference (moon is at a right angle to the sun)

Explain the difference between a valley and continental glaciers. Give an example of both.

Valley: Commonly originating from mountain glaciers or icefields, these glaciers spill down valleys, looking much like giant tongues. Valley glaciers may be very long, often flowing down beyond the snow line, sometimes reaching sea level. >>Tonsina Glacier in Alaska Continental glacier - Forms during ice age and in higher latitudes. Extends to lower latitudes >>Present: Greenland and Antarctic ice sheets

Explain the formation and accumulation of carbonates in soils.

When primary materials are weathered into secondary materials they often become water and carbonic acids. Rain is always slightly acidic and can bring in carbonic acid. Thus, there is carbonic acid in soil from the chemical weathering of bedrock that makes it up

What are the major reservoirs of water (and fresh water) on earth? What are their relative sizes?

largest available freshwater is groundwater 30% technically greatest is ice and glaciers but that is not accesible 68 % lakes and rivers are very small 1.2% atmosphere is smallest .02%

What is the origin of ground water? What steps did it have to go through to become groundwater?

meteoric water from precipitation in the form of rain or snow, to become groundwater, water must infiltrate the soil and be leached through the soil in the saturated area