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97 Cards in this Set
- Front
- Back
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Internal surface processes |
Plate tectonics, uplift If they are balanced with external surface processes then the landscape is in equilibrium |
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External surface processes |
Sun, wind, temperature changes (due to latitude, altitude, etc.) |
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Processes that wear down moutains |
Mass wasting events, freeze thaw, erosion, all these processes are the result of external forces and counter uplift |
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Processes of plate tectonics |
Earthquakes, volcanism, these are the results of internal forces |
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Principle of isostasy |
Balance of pressure between the crust and upper mantle. The continental crust is less dense than the mantle rock, so it's buoyant. As erosion occurs, this buoyancy will cause uplift to occur. |
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Surficial geology |
Composition of landforms, consisting of rocks that have been revealed by erosion or extrusion, or sediments deposited during the Neogene |
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Plane table and alidade |
Optical surveying tools that are used to generate benchmarks and other elevation point data |
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Modern surveying instruments |
Total station Laser range finder |
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Remote sensing |
Measuring characteristics of the Earth's surface from a distance |
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Active remote sensing |
Measuring the earth's surface using an energy source and a detector Ex: SAR, SRTM, LiDAR |
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Methods of active remote sensing |
SAR- Satellite scans an area of the earth's surface, the light bounces back and the detector can sense it and tell angles, distance, etc... SRTM- satellite receives two images to two antennas at the same time, producing a single 3D image LiDAR- Airborne scanning laser, very good in areas with vegetation |
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Passive remote sensing |
Measuring energy emissions from the earth's surface |
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Methods of passive remote sensing |
Landsat- Depending on what areas are covered in, they emit different amounts of heat/infrared light. Landsat can measure this. |
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Methods of relative dating |
Superposition of sediment layers/landforms Landform degradation Lichenometry |
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Methods of numerical dating |
Annual layers: tree rings, varves Cosmogenic dating: radiocarbon, other in situ cosmogenic isotopes Burial dating: Luminescence dating Radiometric dating: radioactive isotopes trapped in rocks and minerals |
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Soil formation |
Only occurs when rate of weathering > rate of erosion |
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Weaknesses in rocks |
Bedding planes Foliation planes Planes of cleavage Mineral boundaries |
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Jointing |
Breaking of rocks along planes oriented relative to stress |
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Exfoliation |
Sheet jointing, breaking of rock into sheets parallel to Earth's surface. A type of weathering that results in almost immediate erosion. |
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Oxidation/Reduction |
Change in ionic charge of a cation, driven by redox potential and the amount of free oxygen in the water |
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Hydrolysis |
Reaction of H+ or OH- with primary minerals to form secondary minerals |
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Saprolite |
In situ chemical weathering without soil formation. Happens where chemical weathering rate is fast, but erosion rate is slow |
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Kaolinite |
The end product of chemical weathering of feldspars. Forms after illite clay weathers, has a 1:1 structure, all potassium ions have been removed, has hydrogen bonding between sheets making it very strong and stable. |
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Biological weathering |
Disaggregation and translocation of rock aided by organisms |
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Soil forming factors |
ClORPT- climate, organisms, relief, parent material, topography |
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Primary soil horizons |
O: litter layer A: top soil, high organic content E: Eluviation of clays, silt and sand left behind B: Illuviation C: unconsolidated parent material R: solid rock |
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Soil texture |
Relative distribution of silt, sand, and clay in a soil |
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Soil structure |
The shape of the soil peds (angular, subangular blocky, columnar, etc....) |
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Loss on ignition |
Method of measuring the mass of organic material in the A layer |
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Hydrometer analysis |
Method of measuring grain size distribution |
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Soil forming processes |
Additions: illuviation, deposition or addition of organics Losses: eluviation, erosion Transformation: chemical weathering of the parent material Translocation: downward movement of material in the soil profile, can sometimes have localized upward movement |
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Common soil types |
Forest soils: in places where the soil has had time to develop Grassland soils: Large A layers, no E layer Arid soils: A layer is dominated by dust |
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Entisol |
Thin A horizon with little or no B horizon, are found in young areas where soil hasn't had much time to develop, or where there's lots of erosion and not much deposition |
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Inceptisol |
A horizon and weakly developed B horizon, has a Bw layer (also called a cambic layer), found in fairly young areas |
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Histosol |
Very thick O and A horizons, lots of organics (>25%), reducing environment, found in coastal lowlands where there's lots of standing water. Standing water prevents free oxygen, so no CO2 accumulation, no acidic groundwater, and not much leaching. |
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Spodosol |
Form in conifer forests, very acidic soil, lots of leaching. Thick E horizon, Bh or Bt layer. Bt horizon means there's the accumulation of clays, clay content of parent material has increased by more than 10% |
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Gelisol |
Soil formed above the permafrost, have A and O horizons, but no B horizon or chemical weathering. Cryoturbation occurs, ice formation disturbing the soil. |
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Andisol |
Limited to felsic volcanic deposits, very productive and nutrient rich, but not much actual soil formation occurring |
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Mollisol |
Grassland soils, thick A horizon with thin or absent E horizon, too cold/dry for much decay of organics |
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Alfisol |
Forest soils, thin A and thick E horizons, also have a Bt horizon. Litter produced by forests decays into the soil, making it acidic and causing leaching, so there will be lots of iron oxide and clay accumulation in the B layer. These usually form in areas with young, unconsolidated material, like glacial till. |
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Ultisol |
Forest soils, A-E-Bt horizons with thin A and thick Bt layers. More mature than Alfisols, form in older material. |
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Oxisol |
Tropical soils, essentially just a Bo horizon. Accumulation of oxides and mature clay minerals, lots of water transforms the parent material a lot. |
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Aridisol |
Desert soils, not much moisture due to lack of water. Bk horizon enriched in secondary carbonates which come from leaching in the A horizon and dust on the surface. |
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Vertisol |
Desert soils enriched in expandable clays. Form in monsoon dominated climates, shrinking and swelling of the clays form continuous vertical fractures which produce prismatic structures. |
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Epipedon |
Upper horizon, O or A, the surface you can stand on, is important for identifying Mollisols and Histosols |
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Subsurface horizon |
E or B horizon, important for identifying soils with a diagnostic B layer, like Aridisols |
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Albic |
Very light colored, leached E horizon |
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Argillic |
Bt horizon, accumulation of clay, 10% more than the parent material |
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Spodic |
Bh horizon, accumulation of organics and clays |
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Cambic |
Bw horizon: minor weathering, clay accumulation |
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Calcic |
Bk horizon: accumulation of secondary carbonate |
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Oxic |
Bo horizon: accumulation of Fe, Al oxides to great thickness |
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Fragipan |
Bx horizon: cemented, clay rich horizon |
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Paleosol |
Soils formed in the past |
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Freshwater reservoirs |
Only 3% of water on earth is freshwater, and 2.5% of that is frozen. Of the unfrozen fresh water, most of it is in aquifers that we can't see. |
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Precipitation |
The only process by which water is delivered from the oceans to land |
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SNOTEL station |
Snowpack telemetry station, used to detect how much precipitation falls in remote locations and how much is stored through the winter months |
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Precipitation delivery |
Considered as events, of which we characterize the duration and the intensity |
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Slope failure due to rainfall |
Linear relationship (on a log scale) between rainfall duration and intensity for the threshold of slope failure. Need extremely high intensity events to cause slope failure in short times. |
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Precipitation frequency |
Recurrence interval can be calculate for very high intensity events RI= (# of events on record +1)/rank p=1/RI |
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Delivery of intense precipitation |
Hurricanes Monsoons Cold fronts Orographic effects |
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Monsoon dynamics |
Land heats up faster than water, so the land heats up the moist air coming off the water causing it to rise and form clouds. The clouds build up and precipitation will usually fall in the afternoon. |
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Evaporation and Evapotranspiration |
Prevent a lot of water from ever reaching the surface, explains the observed difference between flow and precipitation Can be measured using evaporation flows or using the water budget |
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Potential evaporation |
Potential evaporation is usually much higher than actual evaporation, but on the ocean the two are pretty much equal |
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Importance of evapotranspiration |
Contributes to hillslope and water table stability. Also contributes to the shrinking and swelling of clays that forms hardpan; a hardened B layer that reduces the rate of infiltration from the surface down to the water table |
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Infiltration rate |
Is greater in soils with a higher permeability, in unsaturated soils, infiltration rate > hydraulic conductivity, for saturated soils, infiltration rate = hydraulic conductivity Infiltration decreases over the course of a precipitation event, while runoff increases |
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Capillary fringe |
The area at the top of the saturated zone where water is pulled up from the water table due to low air pressure in the soil. This makes it so the top of the water table is technically a little below the top of the saturated zone. |
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Porosity |
Vvoids/Vsediment In some clays there's more void space than rock material Tight packing and poor sorting both contribute to low porosity |
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Hydraulic conductivity |
A way of quantifying the permeability of a material, it is a function of the material. Units are always length/time but it's not a velocity. Represented as K |
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Surface flow |
Sheet flow and channel flow Channel flow is Horton flow, where precipitation rate is too high for water to infiltrate, and saturation flow where there's overland flow because the ground is saturated |
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Hyporheic flow |
Incised stream channels that direct ground water toward them, is normally found at great elevations where the water table is at great depth |
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Watersheds |
Consist of divide and slopes, HILLS DO NOT EXIST!!!! |
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HIllslope composition |
Determined by the rate of weathering vs erosion, where erosion outpaces weathering slopes will be composed of bedrock, where weathering outpaces erosion they will have soil |
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Strength |
A directional property of rock, compressive, tensile, and shear strength. Can be diminished by fractures, lithologic discontinuities, bedding planes, and foliation |
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Shear strength |
Important for defining failure planes, is calculated by SS = cohesion + effective normal stress (tan angle of internal friction) |
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Effective normal stress |
A factor of normal stress (weight/area) and water pressure |
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Diffusive properties |
Slow processes that lead to the diffusion of hill slope profiles. Includes rain splash, sheet wash, and creep |
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Creep |
Slow movement downslope, can be caused by animal burrows, frost heave, or permafrost creating an impermeable layer above which the slope will fail |
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Mass movements |
Flows: Earth flows (slow), debris flows (fast), no well defined shear plane Slides/slumps: rotational, translational, well defined shear planes, blocks of material move together Falls: Topple (slow), fall (fast) occur on very steep slopes |
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Rotational slide |
Have a well defined head scarp and a bulging toe at the other end. Common on coast lines where wave action can remove material at the bottom and increase the driving stress. |
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Lateral spread |
Failure of stiff sediment overlaying soft, deformable sediment |
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Local landslides |
Oxbow lane: due to undercutting by the river Irondequoit bay: water pipe failure saturated hill slope |
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Flows |
Movement of material moving as a viscous fluid, no resistance to shear Debris flows start as small flows when shear and shaking increase pore water pressure, drive grains apart, and turn material into a viscous fluid. The small slopes keep moving downslope and growing, the only way to really stop them is with a change in slope. |
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Flow matrix |
Must consist of fine grained sediments that can retain the high pore pressure |
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Driving stress |
Parallel to the failure plane, pulls material downslope |
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Resisting stress |
Cohesion + effective normal stress*internal friction |
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Factor of Safety |
Resisting stress/driving stress Failure occurs below 1, below 1.2 is at risk of failure |
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Processes that increase driving stress |
Increase in hillslope angle, undercutting, removal of lateral support |
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Processes that decrease resisting stress |
Reduce cohesion by weathering or removal of vegetation, reduce effective normal stress by increasing pore-water pressure |
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Stabilizing sloeps |
Install perforated pipes to lower the water table and increase effective stress Line slopes with fabric to prevent water from entering (can enter farther up slope though so slopes normally have to be dewatered anyways) Rip rap to absorb wave action, normally just slows down erosion, doesn't stop it |
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Dominant weathering type |
Physical weathering dominates in cold dry climates, chemical weathering dominates in warm wet climates, very little weathering in warm dry climates, a mix in moderate climates, no wet cold climates exist |
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Freeze-thaw |
Breaking of rocks by phase changes of water. Water in a fracture will freeze at the top first, so the fractures will increase in size at depth, making the fractures deeper and eventually causing them to intersect, so frost shattering occurs |
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Thermal expansion |
Breaking of rock due to heating and cooling. Rocks are poor conductors of heat, so a temperature gradient will form between the interior and exterior, this creates small scale jointing called spalling near the surface. |
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Grus |
Small equal sized grains that can be formed by spalling. Minerals weather at different rates, so as the less resistant ones start to wear away, the more resistant ones will break off. |
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Tafoni
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Honeycomb weathering pattern, forms in sandstones due to the growth of salt crystals in void spaces |
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Goldich's weathering series |
The opposite of Bowen's reaction series. Mafic rocks are less stable and more likely to weather at the surface. |
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Solubility of ions in water |
Water must be basic to dissolve silica, acidic to dissolve calcium carbonate, and at either extreme to dissolve aluminum oxide |
