Surface Water Stream landscapes, erosion and deposition.
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Transcript of Surface Water Stream landscapes, erosion and deposition.
Surface WaterSurface WaterStream landscapes, Stream landscapes,
erosion and depositionerosion and deposition
The Water Cycle Water constantly moves among the
oceans, the atmosphere and on land. This unending circulation of Earth’s water supply is the water cycle.
Evaporation- liquid water to water vapor Precipitation- water vapor to liquid water Infiltration- water absorbed by land (soil,
cracks in rocks) Runoff- water flowing over land
ErosioErosionn Erosion is the Erosion is the
transport transport of of weathered weathered materialmaterial
Caused by Caused by water, wind or water, wind or glaciers.glaciers.
GravityGravity The root cause of all erosionThe root cause of all erosion Materials falling downhill are Materials falling downhill are
called called Mass MovementsMass Movements ExamplesExamples
– LandslidesLandslides– AvalanchesAvalanches– mud flowmud flow– rock fallrock fall
RUNNING RUNNING WATERWATER The most common agent of The most common agent of
erosion on Earth’s surfaceerosion on Earth’s surface Streams or water flowing Streams or water flowing
over the ground pick up over the ground pick up and move material.and move material.
These particles weather These particles weather rocks from rocks from abrasionabrasion
Stream FormationStream Formation Run-off is the Run-off is the
flow of water flow of water over the groundover the ground
Run-off results Run-off results in the formation in the formation of streamsof streams
Streams that Streams that flow into other flow into other streams are streams are called called tributariestributaries
Stream velocityStream velocity Velocity is fastest at the top centerVelocity is fastest at the top center Slowest near the stream bedSlowest near the stream bed Velocity is fastest at the outside of a Velocity is fastest at the outside of a
turnturn Results in rapid erosion and carves Results in rapid erosion and carves
out the deepest part of streamout the deepest part of stream
MeandersMeanders As a stream flows As a stream flows
across the flood across the flood plain, it meanders, plain, it meanders, or curves back and or curves back and forthforth
This is caused by This is caused by erosion over time. erosion over time.
Point bar- deposition occurs on the inside of Point bar- deposition occurs on the inside of the curve where flow slows downthe curve where flow slows down
Cut bank- erosion occurs on the outside of Cut bank- erosion occurs on the outside of the curve where flow is fastestthe curve where flow is fastest
Oxbow lakesOxbow lakes When a meander gets extreme it will When a meander gets extreme it will
erode back on itself and form an oxbow erode back on itself and form an oxbow lakelake
Carrying CapacityCarrying Capacity How much material a stream can carry How much material a stream can carry
relates to the velocity (speed) of water.relates to the velocity (speed) of water.
Particle sizeParticle size Higher velocity = larger sediment Higher velocity = larger sediment
can be carried down streamcan be carried down stream As the stream slows, it deposits larger As the stream slows, it deposits larger
particles.particles.
Page 6 ESRTPage 6 ESRT
Stream VelocityStream Velocity…(see page 6 of …(see page 6 of ESRT)ESRT)
As stream As stream velocity velocity increases, the increases, the volume and sizevolume and size of sediments of sediments being carried being carried increases.increases.Velocity of stream
Volume and particle size
Conversely, as stream velocity Conversely, as stream velocity decreases, the settling rate decreases, the settling rate
increases.increases.
Coarse gravel Finer sand
Finer silt Finest clay
Incoming stream with sediments
STOP!STOP!
River River DepositionDeposition DepositionDeposition is the laying down of is the laying down of
weathered and eroded sediments weathered and eroded sediments (bits and pieces of larger rock (bits and pieces of larger rock masses).masses).
Occurs when velocity of the Occurs when velocity of the erosional agent (water, wind, erosional agent (water, wind, glaciers) decreasesglaciers) decreases
Most deposition occurs in bodies Most deposition occurs in bodies of water.of water.
River depositsRiver depositsDeltas -Deltas -
triangular fan triangular fan shaped shaped deposits that deposits that develop as a develop as a stream or river stream or river flows into a flows into a larger body of larger body of water water
Alluvial fans Alluvial fans –– same kind of same kind of deposits but on deposits but on landland
GLACIAL GLACIAL EROSIONEROSION
As a large mass of ice (at least 100 ft As a large mass of ice (at least 100 ft thick) moves downhill, from gravity, it thick) moves downhill, from gravity, it picks up rock material.picks up rock material.
The material grinds against and The material grinds against and scratches the underlying rock.scratches the underlying rock.
This is called abrasion.This is called abrasion. There are two types of glaciers, valley There are two types of glaciers, valley
glaciers and ice sheetsglaciers and ice sheets
This is a This is a valley glaciervalley glacier, which flows , which flows
like a stream, down hill.like a stream, down hill.
Streams cut V-Streams cut V-shaped valleys due shaped valleys due to downward to downward erosionerosion
Glaciers cut U-Glaciers cut U-shaped valleys shaped valleys due to sideways due to sideways erosionerosion
V
U
http://www.youtube.com/watch?v=FIn0UoeDyVg
YOSEMITE VALLEY, California
Deposition by GlaciersDeposition by Glaciers
As a glacier retreats (ice melts), As a glacier retreats (ice melts), it drops all the material in and it drops all the material in and on it.on it.
Note: the glacier Note: the glacier nevernever moves moves backwards, the front just backwards, the front just melts melts back.back.
A variety of deposits are left A variety of deposits are left behind, some are sorted and behind, some are sorted and some are unsorted.some are unsorted.
GLACIER
animation