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117 Cards in this Set
- Front
- Back
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weathering
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-the decay or breakdown of rocks and their minerals into smaller fragments
-occurs with no movement -occurs from surface inward -allows water, air, and other chemicals in, and weathering products out solid rock ---> regolith--->sediment--->soil -first step in erosion process |
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ajoint
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a crack or fissure along horizontal or vertical planes in a rock mass that divides the rock into large blocks
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mechanical weathering
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-destruction of rock through physical stresses
-rocks break into small pieces, surface area of rock increases -no chemical changes, but rock is disintegrated -weakens internal structures -occurs in cold and dry environments 5 types: frost wedging, biological, temp fluctuations, salt crystal growth, exfoliation -occurs faster in cold and dry environments |
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frost wedging
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-most common form of mechanical weathering
-major factor where the temp fluctuates above and below the freezing point -water flows into joints in rock and expands when it freezes |
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exfoliation
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-mechanical weathering
-concentric layers peeling off of a rock -pressure release -most common in igneous or metamorphic rock such as granite -biggest weathering feature on earth -Squamish BC |
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salt-crystal growth
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-mechanical weathering
-salt in rocks weakens mineral bonds, loosening sediments (often sand) which erode through wind or water -often occurs in sandstone like the chuckanut formation in Bham -Mesa Verde villages |
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chemical weathering
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-changes rock by altering its chemical composition
-rock structure weakens as materials are removed or transformed -makes mechanical weathering and other processes easier -occurs faster in warm and humid environments |
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hydrolysis
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-a chemical weathering process affecting silicate minerals
-water ionizes slightly and reacts with silicate minerals -silicate minerals in rocks change form (to clay) or dissolve |
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oxidation
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-chemical reaction
-removal of an electron, addition of an oxygen atom -rusting, increase in volume |
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carbonation
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-chemical weathering
-dissolution of carbonate rocks (Limestone) -CO2 dissolves in water forming carbonic acid -this acid dissolves minerals |
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spheroidal weathering
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-type of below ground chemical weathering
-corners of jointed rocks become rounded over time -rock changes from a rectangular to more round shape -water can act on 3 surfaces on corners, 2 surfaces on edges -hydrolysis occurs and turns into rounded rocks -can only act on one surface |
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mass wasting
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-the geomorphic process by which material moves downslope under the force of gravity
-take place over timescales of seconds to years -types: solifluction, earthflow, mudflow, slump, debris flow, debris slide, slow creep, rockfall -draw diagrams |
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rockfall
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-process from which rocks break free from cliff faces and rapidly tumble
-dry materials, happens instantaneously -controlled by rock strength and weathering |
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landslides
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-mass movement that has a well defined zone or plane of sliding
-slumps is when the materials stay together -somewhat rapid to slow -little to lots of water |
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slump
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-landslide where rock and sediment rotates and moves down slope along clave concave to surface
-happens on slopes with soft deposits in clay and shale |
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debris slide
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-mass of rock regolith and soil that moves downhill
-no fluid movement -Hope slide BC, Kelso |
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mud flow
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-fine textured sediments
-move very quickly down slope -potentially hazardous -occur after heavy rainfall or snow melt -Mt Baker highway mudflow -called Lahar in volcanoes |
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debris flow
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-mud, boulders, trees
-flowing downslope -associated with heavy rainfall, broken pipes -hazardous and destructive -Colorado debris flow and Italy event |
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soil creep
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-a long term process
-force of gravity slowly pulls soil particles downhill -slowest mass wasting process |
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solifluction
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-where water logged soil moves slowly downslope over impermeable material (frozen soil or rock)
-occurs in paraglacial environments -occurs mostly in colder environments |
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colluvium
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-the general term for unconsolidated material deposited on slope
-typically angular, unsorted (any material being driven down by gravity) -gravity is the key player |
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talus
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-piles of rocks and debris that accumulate from repeated rock falls
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avalanche
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-large mass of snow that suddenly slides down a mountainside
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perennial stream
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water runs all year
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ephemeral stream
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water runs only part of the year
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tributary
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a stream or river that runs into a larger stream or river
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confluence
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-the point at which the two streams merge
-if the two tributaries are of approximately equal size the confluence may be called a fork |
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drainage divide
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-an area of raised land that forms a separating rim between two adjacent drainage basins -control where precipitation drains
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drainage basin
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-the geographical area that contributes groundwater and runoff to any particular stream
-vary in size and relief -seperated by topographic barriers called watersheds -smaller within larger -4 types: dendritic, rectangular, trelis, radial |
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dendritic drainage
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-develops in areas with uniform rock structure
-looks like a tree |
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rectangular drainage
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-found in regions that have undergone faulting
-jointed and faulted rock |
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trelis drainage
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-extreme folding of rock layers
-Appalachian Mountains |
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radial drainage
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-develops around a central elevated point
-rounded upland like volcano |
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stream ordering
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-represents stream size -smallest streams in basin order 1
-order rises when 2 streams of same order come together at confluence stream discharge -(and how to calculate!) |
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flood stage
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-stream discharge increases so that water spills out of channel onto adjoining ground
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rill
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small drainage channels that are cut into hill slopes by running water
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gully
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created when streams cut into a mountain slope
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ravine
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-created when gullies enlarge
-very small valley with steep sides |
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canyon
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-ravines that have gone through heavy erosion over time
-deep and broad |
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alluvial fan
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-large fan shaped terrestrial deposit of alluvial sediment on which a braided stream flows over
-form as stream load is deposited because of a reduction in the velocity of stream flow -Kluane Lake, Canada -stream sweeps side to side over time making fan shape -most common in desert climates -when energy is released and comes to a standstill |
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river floodplain
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-lands adjacent to the stream that is subject to flooding when a stream overflows its banks
-natural levees formed by deposit of coarse sediments during flood |
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dissolved load
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-mineral ions that are carried in solution and are invisible during transport in a manner similar to dissolved sugar in water
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suspended load
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-sediment that floats along in the stream
-usually consists of clays and silts held up within the water by turbulence -water flows in a very irregular and disorderly way |
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bed load
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-larger particles such as sand and gravel that roll, slide or bounce along the channel bed in a process called saltation -dominates in mountain streams where slopes are steep and stream velocity is high
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meander
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-when streams erode horizontally and cutbanks form on outside (fast) while point bars form on the inside(slow) -result of centrifugal force
-usually found in areas of low elevation |
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pools and riffles
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-a segment where the water is deeper and slower moving
-a segment where the water is shallow and more turbulent -occur on moderate gradient slopes -most common on lower order streams -rhythmically spaced -occur on the outside |
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horizontal migration
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-migration of a river channel
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braided stream
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-shallow stream channel that is subdivided into a number of continually shifting smaller channels
-separated by bar deposits -multiple channels with mid-channel bars -often the result of excessive sediment delivery to stream -deposition increases as gradient decreases -streams get "choked" with material and choose a new direction of least resistance |
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V-Shaped Valley
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formed when a stream begins to downcut vigorously in an attempt to reach a state of equilibrium (Grand Canyon)
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U-Shaped Valley
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-V-shaped valleys which are formed by continental ice sheets
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cutbanks and point bars
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-cut-banks form on the outside of the stream (fast) and point bars form on the inside (slow) during stream meandering
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oxbow lake
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-abandoned stream channel cut off from rest of stream by meandering process
1st- meander forms 2nd- cutoff develops 3rd- oxbow lake forms -ex: Mississippi River |
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alluvium
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-sediment deposited by a stream
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stream reaches (upper, middle, lower)
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-upper reaches has higher gradient and more velocity than low order streams
-middle is when slopes decrease which slows velocity and begins to meander with depth width and discharge increasing -lower reaches: trunk stream is fully developed and has high order with low stream gradient with very high discharge and major flooding |
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water velocity
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slope steepness or gradient is the largest factor in water velocity
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low slope/gradient
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low water velocity, greater depth, thick deposition
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high slope/gradient
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high water velocity, shallow depth, low discharge
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delta
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-a low level plain that develops where a stream flows into a relatively still body of water so that its velocity decreases and alluvial deposition occurs
-smaller particles farther out -Nile River, Mississippi River Delta |
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well sorted
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sediment sizes are similar
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poorly sorted
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the sediment sizes are weak
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distributary channels
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-streams that branches off and flows away from a main stream channel
-common feature of river deltas -happens when streams near lake or ocean -funnels sediments |
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entrenched meanders
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-a deepened meander of a river which is carried downward further below the valley surface in which the meander originally formed
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levee
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an engineered structure along a river that effectively raises the height of the river bank and thus confines flood discharge
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firn
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-snow that goes through weight and partial melting
-the compact, granular substance that is the transition stage between snow and glacial ice accumulation -ablation |
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glacial mass budget (or balance)
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-the balance in glaciers between the input of snow and firn (accumulation) and the loss of ice due to melting and calving (ablation)
-a glacier grows where the budget is positive and retreats when it is negative |
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internal deformation
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-movement related to the fact that the interior of a glacier behaves like a plastic that can be shaped and manipulated
-continues even if the glacier is melting or retreating |
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basal slip
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-when high amounts of meltwater accumulate at the base of the glacier, thus providing a lubricant between underlying rock and ice mass
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crevasse
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-a deep crack in a glacier, mostly at the top
-form when glaciers travel over a step section of valley |
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glacial advance
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when the leading edge of a glacier is able to move faster than it melts
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glacial retreat
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-when the addition of snow is less than the losses of ice
-reveals the glacial landforms |
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ice cap
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-continuous sheet of ice covering entire landscape
-Mt. Baker (continental glacier) |
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ice field
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buries all but tallest mountains
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cirque
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-bowl like features on mountain flanks
-top of glacial valley, cliffs on 3 sides (Alpine cirques) |
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alpine glaciers
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-erosional
-a glacier in mountainous regions that flows down pre-existing valleys -glaciers exist becuase of the mountain -higher elevation=more precipitation, colder temps -cirque, tarn, arete, horn, glacial trough, hanging valley |
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continental/valley glaciers
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-an enormous body of ice that covers a significant part of a landmass
-ice sheets, ice caps, ice fields, tidewater glaciers(valley), piedmont glaciers(valley) |
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a large landmass / ice sheets / Greenland and Antartica
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-when glaciers go through erosion and deposition they create large landmasses
-Greenland ice sheet lost due to warming |
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glacial striations
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the long straight scratches formed when large rock fragments from a glacier moves
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glacial grooves
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deep furrows in rock due to glacial abrasion (erosional)
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glacial plucking
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-a glacier rips large rocks or boulders from the ground as it moves
-carried within the ice or are frozen to the bottom of glacier and later are dropped when retreat occurs |
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glacial erratics
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-large boulders that have been plucked and transported a great distance before they are deposited
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glacial trough
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U-shaped valley eroded by a glacier
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glacial till
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-a form of glacial drift
-sediment directly deposited by a glacier, wide range of particle sizes, no layers |
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glacial outwash
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-sediments deposited by water out and under a glacier as it melts
-forms Outwash Plain, flat feature in front of former glacier |
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roche moutonnée
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-erosional landform
-a landform produced by glacial abrasion and plucking that has a shallow slope on one side and a steep slope on the other side -Mt. Erie |
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tarn
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-a small lake that forms within a glacial cirque
-lakes on bedrock eroded by a glacier |
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arete
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a sharp ridge that forms between two glacial cirques
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hanging valley
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-side trough along main trough
-possible waterfall -elevated U-shaped valley formed by a tributary alpine glacier |
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horn
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-mountain with 3 or more aretes at summit
-Canadian Rockies , Matterhorn |
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moraine
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-an accumulation of till
-a winding ridge-like feature that forms at the front or side of a glacier or between two glaciers |
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lateral moraine
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forms along former edges of glacier
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terminal moraine
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-forms along front of former glacier
-marks the maximum advance of a glacier |
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recessional moraine
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formed as glacier recedes
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medial moraine
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forms between 2 glaciers
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stream discharge
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-the volume of water passing through a river channel during a certain period of time
Q = W x D x V -Q equals stream discharge usually measured in cubic meters per second, W equals channel width, D equals channel depth, and V equals velocity of flowing water. |
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hydrograph
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shows discharge over time
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flooding
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stream discharge increases so that water spills out of channel onto adjoining ground
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flood return interval
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-time between events of a given magnitude (annual flood, 50 year flood, 100 year flood)
-larger floods occur less frequently |
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meandering process
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-high suspended load
-curving channel -the flatter it gets, the more it meanders -maximum current on outer edge -most erosion occurs along the stream bed -deposition increases as gradient decreases |
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natural levees
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-formed by deposits of coarse sediments during flood
-found in floodplains |
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glacier formation
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1. begin as snowfall
2. with weight and partial melting, snow turns to firn 3. further compaction, ice crystals align, become dense glacial ice 4. the ice begins to flow (plastically) under its own weight 3. |
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Glacial Mass Budget Diagram
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zone of accumulation - top of glacier where temps are cooler (input > output)
Zone of Ablation: lower part of glacier where temps are higher (output>input) Equilibrium Line: point on glacier where input =output Flow: a glacier will bulge out to the sides under its own weight and flow ablation: output of the glacier |
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glacial movement
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-like jello, a glacier will bulge out to the sides under its own weight
-most glacier movement is internal deformation |
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erosional landforms
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U-shaped valleys, hanging valleys, cirques, horns, aretes
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depositional landforms
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till, moraines, outwash plains, erratics, drumlins, kettles
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Missoula Floods
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-western Montana covered by a lake/ice sheet
-water burst through glacial damn and flooded Idaho, Oregon, Washington towards Pacific Ocean -waves and chunks of ice tore away soils and mountainsides, deposited ripple marks, created scablands of E.Washington and carved out river Gorge |
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Glacial History
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-Pleistocine Age
-1/3 of land covered in glaciers -sea level dropped -entire Puget lowlands were modified during this time -maximum extent of glacial ice was in the midwest/northeast |
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Glacier loss and water supply
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-without glacier runoff we may not have enough water to meet demand
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proxy data and climate studies
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-ice coring can give clues as to how fast Greenland will melt
-can measure CO2, methane, nitrous oxide -only medium that collects the atmosphere itself -thickness of layers will tell you how much snow fell that year -rising greenhouse gas levels |
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Extreme Ice: mountain glaciers and sea level
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-mountain glaciers almost everywhere will simply disappear
-from the loss, sea levels will rise by almost a foot, displacing millions of people around the world -largest cost loss of these huge natural reservoirs of fresh water, water that one-sixth of the world's population depends on |
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township/range system
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-section/township(6x6)/range
-found backwards |
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contour interval
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-found on bottom center of map
-elevational change between contour lines -every 5th contour is a thicker line and called an index |
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principle meridian
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reference or beginning point for measuring east or west ranges
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baseline
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reference or beginning point for measuring north or south townships
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topography
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the shape of the land surface
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topographic map
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a two dimensional representation of a portion of the three - dimensional surface of the earth
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map scale
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the ratio between the distance on a map and the same distance on the ground
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representative fraction
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numerical scale of a map indicating relationship of distance on a map and the corresponding distance on the ground
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