weathering, erosion, deposition
where does deposition mainly occur by?
streams, glaciers, waves/currents, wind, mass movements
glacial erosion features/evidence
sub-rounded and scratched, u-shaped valleys, glacial erratics- boulders, unsorted sediment
alluvial fan
stream deposition on land
what occurs when a rock is crushed into a oil of fragments? total surface area ___________ and chemical composition ___________
increases, remains the same
the formation of soil is primarily the result of
weathering and biological activity
types of chemical weathering
1. oxidation 2. hydration 3. carbonation
types of weathering
1. physical/mechanical 2. chemical
most common places for wind erosion
- arid regions, like deserts - lake or ocean coastlines
glacier surrounding terminology
- moraines (ground and terminal) - drumlins - kettle lakes - outwash plains
types of physical weathering
1. root action 2. frost action/wedging 3. exfoliation 4. abrasion 5. wave action
energy transformation in an erosional-depositional system
-high kinetic energy = erosion -low kinetic energy = deposition -dynamic equilibrium: rate of erosion = rate of deposition
weathering occurs when rocks are exposed to...
1. air (atmosphere) 2. water (hydrosphere) 3. living things 4. pressure changes
factors affecting the rate and type of weathering
1. exposure 2. particle size 3. mineral composition 4. climate
evidence of erosion
1. if sediment has been moved from its source 2. transported material have distinct properties that indicate the agent of erosion 3. streams: the sediment is rounded and smooth (the longer the sediment is eroded -> smoother and rounder)
velocity of streams rules
1. if sediment is to be transported by water, the water has to be moving 2. as velocity of a stream increases, the AMOUNT of sediment transport increases (direct) 3. as a velocity of a stream increases, the SIZE of transported particles increases (direct)
what affects the rate of deposition?
1. size: larger particles are heavier and settle faster than small particles; particle size increases, settling time decreases 2. shape: rounder sediments settle faster than flat particles bc less surface area against friction 3. density: high density particles settle faster
what determines stream velocity?
1. slope/gradient (as slope increases, velocity increases) 2. discharge (volume of water increases, velocity increases) 3. position in stream (top = fastest, bottom = slowest)
ways that stream carry sediment
1. solution 2. suspension 3. rolling and bouncing
distinct properties of transported material
1. wind: rounded and pitted 2. glacier: sub-rounded and scratched 3. gravity: sharp and angular
a sedimentary deposit produced by wind erosion is most likely composed of 1. shells of varying size, shape, and composition in isolated mounds 2. a range in particle sizes from 1.0 to 10.0 cm in diameter in thick layers 3. sorted fine-grained particles in cross-bedded layers 4. flat, angular boulders in unsorted piles
3
**STREAM LANDSCAPE FEATURES DIAGRAM
PAGE 56, 57, 58, 59
natural levees
a deposit of sand on either side of a river
oxbow lake
a meander that has been cut off from the river
soil
a mixture of rock particles and decayed organic material on earth's surface that supports rooted plants; over time soil develops horizontal layers with a distinctive profile
sand dune
a pile of wind-blown sand created by wind; layers or mounds that sand is deposited in; have a gentle slope facing into the wind and a steeper slope on the side that the wind is; cross bedded sandstone
tributary
a smaller stream that flows into a larger stream
barrier island
a thin strip of land created by deposition
which type of climate has the greatest amount of rock weathering caused by frost action?
a wet climate in which temperatures alternate between below freezing to above freezing
man-made erosion
activities including deforestation, overgrazing, construction, poor farming increase exposure to agents of erosion
water waves and current examples
beaches, barrier islands, long shore current
kettle lake
block of ice left by after a glacier melts and fills with water
chemical weathering
breakdown of rock by chemical action that results in a change in mineral or chemical composition
glaciers
carries sediment by scraping and dragging it along the surface (glacial grooves)
exfoliation
changes in temperature cause the rock to expand, contract, and eventually break
which types of weathering and erosion are primarily responsible for the formation of caves?
chemical weathering and groundwater flow
climate
chemical weathering increases in warm, humid climates; physical weathering increases in cold, humid climates; dry/arid very little weathering
when wind and running water gradually decrease in velocity, the transported sediments are...
deposited over a period of time, and are sorted by size and density
mineral composition
different minerals have different resistance to weathering, hard = more difficult to weather, soft = easier to weather
solution
dissolved minerals are transported this way
running water
dominant moves over land and picks up and carries weathered rock material (watershed, tributaries) evidence: rounded, smoothed, polished, v-shaped valleys
when winds slows down or stops, the sediment it carries is ___________
dropped/deposited (only sand and smaller sized sediment)
which is the direction of wave movement in the barrier islands?
east to west
oxbow lakes are generally formed by
erosion along the outside banks of a curve in a meandering stream
long shore current
flow of water that can carry sediments parallel to the shore
unsorted, angular, rough-surfaced cobbles and boulders are found at the base of a cliff. what most likely transported these cobbles and boulders?
gravity
what is the top layer of soil?
humus; consists of weathered rock particles and organic material from plants and animals
which agent of erosion transported the sediments that formed moraines?
ice
what are sediments moved by?
ice, gravity, water, or air
floodplain
land where excess water from river goes to
rolling and bouncing
large solid sediments (sand, pebbles, boulders) are carried this way
wind erosion
loose sediment the size of sand or smaller are moved by wind (most common arid, sand dunes- wind comes from the gentle slope) evidence: rounded and pitted
hydration
minerals in rocks are dissolved by water which creates a new mineral compound
exposure
more exposure/closer to the surface, faster weathering
horizontal sorting
occurs when larger, denser, and more rounded settle out first and the velocity gradually decreases -occurs at a delta: where a stream or river flows into the ocean
mass movement landscape
piles of unsorted, unlayered sediments that have sharped edges
outwash plain
plain formed of glacial sediments deposited by meltwater outwash at the bottom of a glacier
gravity/mass movement
sediment moving down slope due to gravity (ex. rockslide, mudslide, landslide) evidence: sediments that are sharp and angular
during deposition, sediments of similar size, shape, or density get ____________ by type
separated/sorted
root action
plants roots grow through cracks and break the rock
types of soil
residual and transported
carbonation
rocks, especially limestone react with carbonic acid (caves & stalactities)
which agent of erosion creates sorted sediments?
running water
examples of mass movement deposit sediment of all different sizes, shapes, and densities at the _________... resulting in __________
same time, unsorted deposition
what happens when a shoreline has a projection out into the ocean (jetty)?
sand is deposited on the side facing the oncoming longshore current (the water slows down and the sand settles out) the side facing away gets eroded
stream: deposition/erosion
slow=deposition, fast=erosion
suspension
small particles (silt, clay) are lifted up
particle size
smaller particle size, greater surface area and the faster the weathering
transported soil
soil that has been moved from one place to another area (common in NY)
residual soil
soil that has formed from the bedrock beneath it
watershed
the area of land drained by any one stream (drainage area)
physical weathering
the breakdown of rock into smaller pieces without chemical change
weathering
the breakdown of rocks at or near Earth's surface into smaller particles called sediment
when a stream is straight, where is the velocity the fastest?
the center
erosion
the process by which sediments are picked-up and transported
deposition
the releasing or depositing of solid sediment and dissolved minerals
when a stream curves, where is the fastest water?
toward the outside of the curve
valleys eroded by glaciers are __ shaped, valleys eroded by streams are __ shaped
u, v
glacial moraine
unsorted piles of sediment formed at the end and edges of a glaciers (ground and terminal)
jetties and groins are...
used to prevent longshore drift
valleys eroded by streams
v-shaped
sediment is deposited as a river enters the lake because the
velocity of the river decreases
when does deposition usually occur?
velocity or speed of the stream or wind decreases or stops
frost action/wedging
water freezes and expands which causes the rock to break
wave action
waves pounding against rocks - sand and rocks in the waves help to break up the shoreline.
difference between weathering, erosion, and deposition
weathering: the action of breaking down the rock erosion: the transport/movement of the particles deposition: where the particles are placed
drumlin
whale backed hills (oval shaped) of unsorted sediment; glacier game from the direction of steep slope, dropped sediment which created a gradual slope
definition and examples of agents of erosion
what transports the sediment 1. gravity/mass movement 2. wind 3. ice (glacier) 4. ocean waves 5. humans 6. water**
saturation of dissolved minerals
when a body of water becomes 100% filled with dissolved minerals, the water evaporates and minerals settle out
oxidation
when elements (iron) in the rock react with oxygen to create rust
how is a beach created?
when ocean waves slow down as they approach the shore, they move sediments towards the shore
abrasion
when rocks or sediments grind against another rock - stream abrasion: the rounding and smoothing of rocks as they tumble in a stream - wind abrasion: dry climates, the wind picks up sand and blows it against rocks causing 'pitting' (sandblasted appearance)
vertical (gradual) bedding
when sediments settle out quickly -layers develop with sediment size increasing from top to bottom -oceans/lake bottoms
ocean waves
where ocean meets land, waves acts as agents of erosion (evidence: sharp cliffs)
sand dunes are formed by ________ and sand bars are formed by ___________
wind waves
natural sandblasting (abrasion) of surface bedrock in the desert region is the result of
wind erosion