The document discusses various landscape-shaping processes including weathering, erosion, and deposition. It provides details on: - Weathering processes like physical weathering (frost action, abrasion) and chemical weathering (oxidation, hydration, carbonation) break rocks down into sediments. - Running water is the primary agent of erosion, carrying sediments in streams based on factors like gradient, discharge, and particle size/shape. Meanders, floodplains, and deltas are landforms formed by streams. - Deposition occurs when sediment transport capacity decreases, arranging particles from largest to smallest in a process called horizontal sorting. Particle size, shape, density, and water velocity impact deposition rates

2. Introduction
 weathering, erosion, and deposition are a main force behind landscape types
 But they are not the only reason for a plain, plateau, and mountain region to form
o Other factors such as glaciation and tectonic activity lead to landscape building
In New York State, glaciation is one of the main causes of many types of
landscape regions
o the water cycle or hydrologic cycle (see graphic below) is the driving force behind
WED (weathering, erosion, and deposition)
o winds also help form the surface landscape
o But without gravity and the sun this whole process would not occur
Weathering, Erosion, Deposition (WED)

4. The water cycle process looks like
this:
Evaporation  condensation 
precipitation  infiltration 
run-off
Without this process, weathering,
erosion, and deposition would have
a difficult time occurring on
Earth.

5. Weathering
-- chemical and physical processes that
change the characteristics of rocks on the
Earth’s surface.
o also known as the preparation for
erosion .
o for weathering to occur, the rock
sample must change and rock needs to be
exposed to water and air.
o Human processes such as pollution,
(like acid rain) along with the acts of other
living organisms, can cause chemical
weathering to occur at faster rates.

6. Weathering Process
The weathering process occurs when rocks are
exposed to the hydrosphere (water) and
atmosphere (air).
 These agents can change the physical and
chemical characteristics of rocks.
 As rocks are broken down (weathered), they
can be classified as different types of sediments,
which are:
o boulders, cobbles, pebbles, sand, silt, clay, and
colloids.

7. Physical Weathering
Physical weathering -- when rocks are broken in to smaller
pieces without changing the chemical composition of the rock.
 Think of a physical change (e.g., ripping a piece of paper)
-- will change size, but all other characteristics will remain the
same.
 Types of physical weathering:
o Frost action/ice wedging -- breakup of rock caused by
the freezing and thawing (contracting and expansion) of water.
A very similar process occurs on roads, which causes potholes.
o Abrasion --physical wearing down of rocks as they rub or
bounce against each other--most common in windy areas, under
glaciers, or in stream channels.
o Exfoliation --peeling away of large sheets of loosened
materials at the surface of a rock. Common in shale, slate, and
mica.

9. Chemical Weathering
Chemical weathering --when a rock is broken down by chemical action resulting in a
change in the composition of a rock.
 Such as the change a piece of paper would go through after being burned.
 Main agents of chemical weathering are oxygen, rainwater, carbon dioxide, and
acids produced by decaying plants and animals that leads to the formation of soil.
 There are a few types of chemical weathering such as:
o Oxidation -- when oxygen interacts chemically with minerals. Ex.: when a nail
rusts oxygen combines with the iron in the nail to form iron oxide.
o Hydration -- when water interacts chemically with minerals. Ex., when
hornblende and feldspar unite with water they eventually form into clay.
o Carbonation -- when carbon dioxide interacts chemically with minerals.
§ carbon dioxide -- dissolved in water, forms weak carbonic acid.
§ Carbonic acid -- comes in contact with the surface of the earth dissolves large
masses of limestone, creating caves and caverns.
§ Other common terms associated with carbonation are sink holes, karst
topography, stalactites and stalagmites.
 Weathering rates --depend on 3 different factors:
o Particle size/surface area exposed to the surface
o Mineral composition
o Climate

10. Soil Formation
 One of the major products of weathering
is soil
 Soil -- combination of particles of rocks,
minerals, and organic matter
 Soil contains the necessary nutrients to
support plant and animal life
 As a result of the weathering processes
and biologic activity, soil horizons (layers)
form
 Soil horizons vary in depth depending on
an areas climate and weathering rates

12. Erosion
Once a rock material has been weathered, it is ready to be
transported, or eroded. Erosion refers to the transportation of
rock, soil, and mineral particles from one location to another.
· Erosion is different from weathering since erosion has the
moving element.
· The main driving force behind all agents of erosion is gravity.
· Without gravity the other major natural agents of erosion such
as: wind, running water, glaciers, waves, and rain would not occur.
 usually takes many years for erosion to be noticed, such is the
case with the Grand Canyon.
 But it is common to see erosion take place in a quick fashion.
 Ex. --Recent erosion along the California coastline. Many homes
and land has eroded into the Pacific Ocean due to intense wave
action and weak soil/bedrock compositions (erosion).

13. Factors Affecting Transportation of Sediments
 Running water is the primary agent of erosion on Earth
 Most running water is found in streams and rivers
 Many factors affect the movement of sediments in a stream:
•o Gradient (slope), discharge, and channel shape influence a stream’s velocity and the
erosion and deposition of sediments.
 Sediments carried by a stream are almost always rounded due to the grinding action of
the water on the rocks, a process called abrasion
 Streams are usually formed in V-shaped valleys; and deltas, flood plains, and
meanders are results of what a stream can form
 The watershed of a stream is the area drained by a stream and its tributaries (smaller
feeder streams).
 The average velocity (speed) of a stream depends on its slope and discharge, which in
turn can explain the carrying power of a stream.
•o As velocity of the stream water increases, size of the particles carried in the
stream also increases, a direct relationship.
 Streams carry materials in 4 distinct ways:
o Floatation, solution (dissolved particles), suspension (within the water profile), and bed
load (bouncing and dragging along the stream bed. · Meanders -- another very important part of
stream erosion.
o In a meandering stream velocity is lowest (High Potential Energy) along the inner banks
o Along a straight channel segment, water moves the fastest in mid-channel, near the surface.
o But as water moves around a bend, the zone of high velocity (High Kinetic Energy) swings to the
outside of the channel.
o another landform -- an oxbow lake -- can develop-- forming an independent loop that will become
a lake (see below).

14. •meanders are results of what a stream can form
 The watershed of a stream is the area drained by a stream and its
tributaries (smaller feeder streams).
 The average velocity (speed) of a stream depends on its slope and
discharge, which in turn can explain the carrying power of a stream.
•o As velocity of the stream water increases, size of the particles
carried in the stream also increases, a direct relationship.
 Streams carry materials in 4 distinct ways:
o Floatation, solution (dissolved particles), suspension (within the
water profile), and bed load (bouncing and dragging along the stream bed.
· Meanders -- another very important part of stream erosion.
o In a meandering stream velocity is lowest (High Potential Energy) along the
inner banks
o Along a straight channel segment, water moves the fastest in mid-channel,
near the surface.
o But as water moves around a bend, the zone of high velocity (High Kinetic
Energy) swings to the outside of the channel.
o another landform -- an oxbow lake -- can develop-- forming an independent
loop that will become a lake (see below).

15. Oxbow Lake Formation Diagram

16. Valleys Eroded by Streams and Glaciers
 Valleys that have been eroded:
•o by streams are v-shaped
•o by glaciers are u-shaped
Effect of Humans on Erosion
Humans add greatly to the natural processes of land erosion through activities,
such as:
 highway and construction,
 destruction of forests (clear-cutting),
 set forest fires,
 poor landfill projects, etc…
 Today, human activities contribute more than ever to the erosion on the
Earth’s surface.
Deposition
-- Rock particles are deposited somewhere else --the final step in the erosional-depositional
system.
· agents of erosion become agents of deposition
· Final deposition of particles (sediments) usually occurs at the mouth of a stream--a
process called horizontal sorting takes place:
o The sediments that were once carried down the stream are arranged from largest to
smallest.

17. Stream Horizontal Sorting Diagram

18. Factors Affecting Deposition
The major factors that affect the rate of
deposition are:
 particle size, shape, density, and
the velocity of the transporting stream:
•o Size: smaller particles settle more
slowly than the larger particles, due to
gravity. The smaller particles tend to stay
in suspension for longer periods of time.
This form of deposition is called graded
bedding or vertical sorting. The diagram
below shows graded bedding.

19.  Shape: A round sediment compared to a flat
(skipping stone) sediment of equal size will settle faster in
a body of water. The graphic below shows the relationship.
 Density: If particles are the same size but have
different densities the higher density particle will settle
faster
 Velocity:
o If the stream slows down during a drought period, the
carrying power will decrease and the particle sizes carried
and deposited will also decrease.
o If a stream is flowing faster due to flood conditions,
then the carrying power of the stream will increase and the
sizes of particles deposited will increase as well.

22. Glacial Deposition
Glacial ice deposits --very different from
stream (water) deposits.
 Glacial deposits of gravel, boulders,
and sand are unsorted with no layer as in
graded bedding.
 Till which is the accumulation of
sediments carried by a glacier is very
sharp like broken glass.
The diagram below shows the unsorted
nature of glacial deposits:

23. Glacial Deposits Diagram