Studied by 32 people
Weathering
involves the physical breakdown (disintegration) and chemical alteration (decomposition) of rock at or near the Earth’s surface
Mechanical Weathering
Accomplished by physical forces that break the rock into smaller and smaller pieces without changing the rock’s mineral composition.
the disintegration of Earth's materials makes detrital sediments
Frost Wedging
When water enters the joints, alternate freezing and thawing episodes pry the rock apart.
After water works its way into the cracks in the rock, t__he freezing water enlarges the cracks, and angular fragments are eventually produced__.
Salt Crystal Growth
Force exerted by a salt crystal that forms as water evaporates from pore spaces or cracks in rocks can cause the rock to fall apart.
Infiltration of salty waters on rocks or soils from groundwaters or salty seawater.
Sheeting
Also known as exfoliation, it is caused by the expansion(pressure release) of crystalline rock as erosion removes the overlying material(overburdened rock)
Abrasion
Wearing away of rocks by the constant collision of loose particles
This can be due to water, wind, or ice.
Biological Activity
Plants and animals as agents of mechanical weathering
Wedges in rocks and soils form through plant growth (rooting) and motor activities of animals and even humans (like burrowing or shoveling).
Chemical Weathering
Involves a chemical transformation of rock into one or more new compounds.
Decomposition of rocks and minerals by chemical processes
Dissolution
dissociation(splitting) of molecules into ions
the process by which a mineral completely dissolves in water or other acidic solutions
a common example includes the __________ of calcite and salt
Oxidation
reaction between minerals and oxygen dissolved in water
the reaction of oxygen with iron-bearing minerals in rock.
Hydrolysis
change in the composition of minerals when they react with water
occurs when silicate minerals react with water so that the mineral recombines with the water molecule to form a new mineral.
For example, consider the mineral potassium feldspar
Spheroidal weathering
A form of chemical weathering where a generally spherical boulder is cracked & split off into curved layers on a much smaller scale
Climate
? Cold and dry
? High temperature and high rainfall
A factor that affects weathering:
The presence of water which is an important chemical weathering agent increases the rate of weathering.
High temperature enhances chemical reactions.
? What climate causes a slow rate of chemical weathering
? What climate causes a high rate of chemical weathering
Rock Type
A factor that affects weathering:
The minerals that constitute rocks have different susceptibilities to weathering.
Those most stable to surface conditions will be the most resistant to weathering.
Rock Structure
A factor that affects weathering:
rate of weathering is affected by the presence of joints, folds, faults, bedding planes through which agents of weathering enter a rock mass.
Topography
? Steep slopes
? Gentle slopes
A factor that affects weathering:
Weathering may occur more quickly on a steep slope than on a gentle one
? In what kind of slope is physical weathering faster
? In what kind of slope is chemical weathering faster
Time
A factor that affects weathering:
Longer exposure to weathering agents could mean a higher degree of weathering processes have occurred. The rock has been weakened; therefore, easier to be a break.
Length of exposure to agents of weather determines the degree of weathering of a rock
Erosion
the incorporation and transportation of material by a mobile agent such as water, wind, or ice
Deposition
the settlement of material on a definite location; the inability of a mobile agent to transport deposits material.
Running Water
Ocean or Sea Waves
Groundwater
Glacier
Wind
Gravity
What are the basic agents that drive sediment transport?
Hydrologic Cycle
Drainage basin
the area drained by a stream and its tributaries
Divides
boundaries between drainage basins
Laminar flow
fluid travels smoothly or in regular paths
Turbulent flow
irregular fluctuations of liquid
the speed of water is continuously undergoing changes in direction & magnitude
Overland flow
Encompassed by Running Water
surface run-offs
water flow down to a drainage basin due to a drainage divide, form rills and gullies on the surface due to erosion(rill & gully erosion)
can erode before forming rills and gullies by sheet erosion
Streamflow
Encompassed by Running Water
water flow in drainage basins(valley formation)
turbulent flow of water is usually in river channels
Velocity
A factor affecting stream
dictates the ability of a stream to erode & transport
controlled by gradient, channel size & shape, channel roughness and the amount of water flowing in the channel
Gradient
A factor affecting stream
slope of the stream expressed as the vertical drop of a stream over a specified distance
reserves much more enrgy the steeper it gets
Channel
A factor affecting stream
stream path; straight channel can cause smooth stream(smooth erosion) while curved/banked channel can slow the stream and make it turbulent
Discharge
A factor affecting stream
volume of water passin through a cross-section of a stream during a given time
as the discharge increases, the width of the channel, the depth of flow or flow velocity increase individually or simultaneously
Slows the velocity
What happens to the velocity when a channel is widened by soft rock and becomes rough & boulder strewn?
what happens to the velocity when the channel is wide & shallow, increasing friction?
Stream velocity increases
What happens to the velocity when a landslide narrows a channel?
What happens to the velocity when a channel is semicircular?
What happens to the velocity when bridge, piers or other obstructions are put up?
Headward Erosion
Styles of erosion
makes a river longer
happens near its source
surface run-off and flow cause erosion at the point where the water enters the valley head
Vertical Erosion
Style of erosion
makes a river channel deeper
this happen more in the upper stages of a river
Lateral erosion
Style of erosion
makes a river wider
this occurs mostly in the middle and lower stages of a river
Quarrying
Erosion process in running water
involves the removal of blocks from the bed of the channel
Abrasion
Erosion process in running water
bed & banks of a bedrock channel are ceaselessly bombarded by particles carried into the flow
Corrosion/Solution
Erosion process in running water
a procces in which rock is gradually dissolved by the flowing water
Dissolved Load
Running Water: Transport sediment
solution
transportation of dissolved mineral which is moved and dispersed in stream
usually came from groundwater
Suspended Load
Running Water: Transport Sediment
suspension
fine sediments(such as clay) transported in streams as suspended sediments
usually came from flooding/run-offs
Bed Load
Running Water: Transport Sediments
coarse grains
transportation by traction(rolling of gravels such as boulders) and saltation(skidding or jumping movements of smaller gravels such as pebbles)
Bedrock Channel
Running Water: Channel Formation
channel which consists and generally formed by rocks whereas its pattern is geologically structured
definite and uniform structure
Straight Channel
Running Water: Channel Formation; Bedrock Channel
form where a stream erodes sediments in a constant patter without drstic change in its path/flow
Alluvial Channel
Running Water: Channel Formation
watewr path whereas it has no definite patter and it changes its structure
composed of unconsolidated sediments
Braided Channel
Running Water: Channel Formation; Alluvial Channel
form where alarge portion of a stream’s load consists of coarse material(sand & gravel) and the stream has a highly variable discharge
Meandering Channel
Running Water: Channel Formation; Alluvial Channel
form where streams that transport much of their load in suspension generally move in sweeping bends
River valleys, waterfalls, potholes, terraces, gulley/rills
Meanders(exhibit erosion & depositional features), oxybow lake, peneplain
What are the of Erosional Landforms from Running water as an agent of erosion
Alluvial fans/cones, natural leeves, deltas
What are the Depositional landforms from running water as an agent of erosion?
Deltas
Running Water: Deposits According to Agents of Erosion
form where sediment-charged streams enters the realtively still water of a lake, an inland sea, or the ocean
Natural Levees
Running Water: Deposits According to Agents of Erosion
meandering rivers that occupy valleys with broad floodplains, tend to build _____ ______ that parallel their channels on both banks
Alluvial Fan
Running Water: Deposits According to Agents of Erosion
Are fan-shaped deposits that accumulate along steep mountain fronts
When a mountain stream emerges onto a relatively flat lowland, its gradient drops and its deposits a large portion of sediment load
Waves
Ocean or Sea Waves
energy transported to a medium
are caused by energy transferred by wind or storm in the ocean’s surface
Wave Height
Wavelength
Wave period
Characteristics of a Wave
What do you call the vertical distance between trough and crest?
What do you call the horizontal distance between successive crests(or troughs)?
What do you call the time it takes one full wave to pass a fixed position?
Wind speed
Length of time the wind has blon
Fetch or distance that the wind has traveled across open water
What are the factors that affect the Height, Length & Period of a Wave?
Hydraulic Action
Shoreline Erosion Process of Ocean/Sea Waves:
Rock wedging and disintegration due to wave slap
Abrasion
Shoreline Erosion Process of Ocean/Sea Waves:
the sawing and grinding action of the water armed with rock fragments
Corrosion
Shoreline Erosion Process of Ocean/Sea Waves:
dissolution of rocks due to constant wave current
Wave Refraction
Transportation by Waves and Currents:
bending of waves making wave front parallel to the shore
Longshore Current
Transportation by Waves and Currents:
erosion of sediments/soils by angled/oblique wave to the shore
Rip Current
Transportation by Waves and Currents:
Concentrated movement of water that flow in the opposite direction from breaking waves
Wave-cut Cliffs
Wave-cut Platforms
Marine Terraces
Sea Arches
Sea Stacks
What are the Erosional Features from Ocean/Sea Waves as an agent of erosion
Beach
Spits
Baymout bars
Tombolo
Barrier Island
What are the Depositional Features from Ocean/Sea Waves as an agent of erosion
Glaciers
a moving body of ice on land that moves downslope or outward from an area of accumulation
Ice Sheets(continental glaciers)
Types of glaciers:
Cover large areas of the land surface
unconfined by topography
cover Antartica and Greenland
Outlet glacier
when a glacier flows out of an ice sheet, ice cap or icefield
Valley(Alpine) Glaciers
Types of glaciers; Ice Sheets:
bounded by vallewys and tend to long and narrow
can be formed when an outlet glacier forms and slides away from an icefield
Can also be formed on their own, starting from high up on a mountain range and flowing down within the steep V between two peaks
Ice Shelf
Types of glaciers:
a thick slab of ice, attached to a coastline and extending out over the ocean as a seaward extension of the grounded ice sheet
Cirque Glaciers
Types of glaciers:
snow that accumulates in small depressions on the side of a mountain, eventually compacting into glacier ice
when the glaciers are built up and shifted, they erode the depression to form bowl shaped valleys called corries or ______
may sometimes accumulate enough ice to spill over and form valley glaciers
Firn
Glaciers: Glacial Formation
a recrystallized snow that is dense and is in granular form with a texture like coarse sand
basic structure that is pressurized to form glacial ice
plastic flow
basal slip
Glaciers: Glacial Movement
Glaciers move to lower elevations by _______ ____ due to great stress on the ice at depth;
and _____ ____ facilitated by meltwater which acts as a lubrican between the glacier and the surface over which it moves
Plucking
Abrasion
Glaciers: Glacial Erosion
What do you call lifting piecies of bedrock beneath the glacier?
What is the grinding and scraping by sediment already in ice called?
Glaciated Valleys
Glacial Through
Truncated Spurs
Hanging Valleys
Paster Noster Lake
Cirque
Tarn
Col
Aretes and Horns
Rouches Moutonnees
What are the landforms created by glacial erosions?
Glacial Till
Glaciers: Glacial Deposits
deposited as glacial ice melts and drops its load of rock fragments
Stratified Drift
Glaciers: Glacial Deposits
deposited by the glacial meltwater and thus has experienced the sorting action of water
Wind
a relatively insignificant erosional agent
Dryness and scant vegetation are important prerequisites for it to be an effective errosional force
Dunes(Sand Deposits)
Type of Wind Deposits:
Hills or ridges of wind-blown sand
Loess(Silt Deposit)
Type of Wind Deposits:
Extensive blankets of silt that were once carried in suspension
Barchan
Wind: Type of Sand Dune
Transverse
Wind: Type of Sand Dune
Barchanoid
Wind: Type of Sand Dune
Longitudinal
Wind: Type of Sand Dune
Parabolic
Wind: Type of Sand Dune
Star
Wind: Type of Sand Dune
Groundwater
represents the largest reservoir of freshwater that is readily available to humans
erodes sediments chemically rather tham mechanically(Weathering and movement of solution)
Zone of soil moisture
Distribution of Groundwater
area where water is molecularly atrracted and suspends
Unsaturated(Vadose) Zone
Distribution of Groundwater
contains both air and water
water cannot be extracted through wells
Saturated(Phreatic) Zone
Distribution of Groundwater
where all the open spaces in sediments and rocks are completely filled with water
Groundwater
Distribution of Groundwater
water present in the phreatic zone
Water table
Distribution of Groundwater
the upper limit of the phreatic zone(boundary with the valdose zone; “water level”)
Capillary fringe
Distribution of Groundwater
Just above the water table
zone where water can penetrate
Graining Streams
Stream-Groundwater Interaction:
inflow of groundwater through the streambed
higher elevation of water table
receive water from he groundwater system
Losing Stream
Stream-Groundwater Interaction:
lower elevation of water table
water from streambed follow down to groundwater
can be connected ot disconnected
provide water to the groundwater system
(disconnected) may form a buldge in the water table when it is separated from the groundwater system by the unsaturrated zone
Porosity
Factor affecting the storage and movement of groundwater
percentage of total volume of rock or sediment containing pore spaces
Permeability
Factor affecting the storage and movement of groundwater
the ability to transmit fluid
Aquitards
Factor affecting the storage and movement of groundwater
impermeable layers that hinders water movement
Ex. clays have mcuh smaller pores
Aquifiers
Factor affecting the storage and movement of groundwater
Permeable layers that transmit groundwater freely
Ex. Sand & gravels have much larger pores
Specific Retention
Factor affecting the storage and movement of groundwater
the ratio of the volume of water that a given body of rock or soil will old against the pull of gravity to the volume of the body itself
Specific Yield
Factor affecting the storage and movement of groundwater
also known as the drainable porosity
is a ration, less than or equal to the effective porosity
Recharge area
Flow system
water flow underground that replenishes water
