1. Unit #10:
Weathering, Erosion, Deposition

2. Why do rocks weather?
 rocks below the
surface are protected
from the exposure to
wind, water and
biological processes
once uplifted and
exposed rocks begin
to weather

3. Weathering
 the breakdown of rock due to
physical or chemical changes

4. Physical Weathering
 changes the size and/or shape of a
rock, without changing the rock’s
chemical composition
Example: breaking a rock into
smaller pieces
 harder minerals are more
resistant to physical weathering

5. Types of Physical Weathering:
Frost action  alternating temperatures
above and below 0°C, allow water to melt and
freeze, causing expansion of the cracks
Biological Factors  roots of plants can grow
within cracks in the rocks and increase the
crack size, leading to crumbling of the rock
Abrasion  collisions between particles
caused by wind, moving ice and gravity,
these particles act like sandpaper of the rocks

7. Chemical Weathering
 changes in the chemical
composition of rock, thereby forming
new substances.
Example: rusting of iron rich mineral

8. Chemical Weathering
 chemical weather requires heat and water
 some minerals are more resistant to
chemical weathering, such as quartz
 slightly acid water can cause significant
weathering of limestone forming caves
 emissions of atmospheric pollutants such as
oxides of sulfur and nitrogen can cause rain to be
acid and increase chemical erosion
carbonic, nitric, and sulfuric acid are able to
change hard limestone into a soft residue

11. How do soils form?
Soil --> mixture of weathered rock and
organic remains that usually cover
bedrock
Develop through:
 physical weathering
 chemical weathering
 organic activity

12. Nature of soils dependent upon:
 rocks from which it weathered
 local climate
 amount of organic activity (plants
and animals)

13. Soils Horizons
--> distinct layers of
soil created by
different amounts of
organic and
inorganic material

15. Thickness of Soil horizons
 young/immature soils do not show
distinct horizons
 mature soils show distinct A, B,
and C horizons
 arid climates have thin soils
 humid climates have thick soils
 steep sloping areas have thin
soils
gentle sloping areas have thick soils

16. Escarpments in an arid
climate

17. --> Soils must be conserved from wind
and water erosion
--> it takes between 100 and 400 years
for one centimeter of topsoil to form
--> Conservation methods include:
 Contour farming
 Terracing
 Increase vegetation cover
 Wind blocks

18. Types of Soils
Residual soils --> form directly above
the parent bedrock, thinner
Transported soil --> form from
sediments that has been moved into
that area

19. How are weathered Material
Transported?
Sediments --> rocks that have been broken
into fragment, regardless of their size

20. Erosion
--> the transporting of sediments away
from their place of origin and the
depositing of them elsewhere
Force behind erosion: gravity
Example: rock falling from a cliff
Water moving down slope

21. Erosion by Water
Watering is the
primary agent of
erosion on the
Earth’s surface
 each year
streams and rivers
carry millions of tons
of sediments
downstream and
into the oceans

23. Transportation of sediments by water:
1) Solution --> smallest particles
dissolved in the water, can’t be filtered
2) Suspension --> large particles, not
dissolved, can be filtered
3) bouncing and rolling --> largest
particles will travel along the bottom of
the stream channel

24.  Faster moving water carry larger
particles and small particles
 Slower moving water carry small
particles, only

25. The Velocity
of Streams.
 controlled by
the slope of the
landscape and the
volume of water
 Stream
gradient increases,
water velocity
increases
Increase volume of
water will also
increase velocity

26. Discharge
--> volume of
water that is
traveling in a
stream
Increases
with velocity
and volume

28. Speed of water
Equilibrium exists between
the force of gravity and the
friction created by the
channel
In a straight stream,
water will flow the fastest
in the middle of the
channel, less friction

29. Meandering Stream
•
--> curving
stream path
Erosion on the
outside of the
turn, velocity is
fastest
Deposition on
the inside of the
turn, velocity is

34. --> Gentle
valleys, like
Milford, will have
meandering
stream, more
horizontal
erosion
--> Steep
valleys, like
ravine behind
the school, has
straighter
streams, more
vertical erosion

35. Erosion By Wind
--> pick up loose rock materials such as
sand, silt and clay and carry them away
--> occurs in arid climates with little
vegetation
--> erosion of clay and silt
(smallest) particles leaving behind only larger
particles called: desert pavement
--> can also erode by abrasion
--> similar to sandpaper rubbing
against a rock creating angular, but smooth
sediments called: ventifacts

36. Erosion by Ice
--> when the snow during the winter does not
melt during the summer and begins to
accumulate year after year
--> Ice can get up to a mile thick
--> Ice will start to move down slope under its
own weight
--> Glaciers will trap all sizes of
sediments within the ice, creating a massive
piece of sandpaper that will scour the valley it
travels through

39. Evidence of Glaciation
--> Glaciers will deepen and widen preexisting
valley to give them a characteristic U-shape.
--> Stream cut through valleys with
vertical erosion to create a V-shape
Unsorted deposits --> deposition of
sediments of all sizes in one area
Striations --> scratches in the bedrock
caused by the rough undersurface of the
parallel grooves that align with the glaciers
movement
--> In NYS these striation run from NW to
SE, indicating that the last glacial
advancement came from Canada

40. Four Periods of continental glaciation in
the past two million years in NYS
 due to glaciation, NYS is covered
with thick transported soils
The last glacial advancement was the
Wisconsin glacier approximately 11,500
years ago

41. o Created U-shaped valleys
o Rounded mountain tops
o Polished bedrock with striations
o Unsorted sediments
o Long Island and Cape Cod
o Finger lakes
o Thick transported soils
Large miscellaneous boulders called: Glacial
erratic

43. What is depositions?
Deposition --> when
an agent of erosion
deposits, or lays
down, particles and
fragments of earth
materials
 also called
sedimentation
 most deposition
occurs in water

44. Factors that affect deposition
Rate of deposition is dependent upon
factors such as:
 Size
 Shape
 Density
 Speed of the transporting material

46. Particle Size:
--> Inverse relationship
 large a particles settle first, while
small particles settle last
 particles in solution or suspension
may stay suspended indefinitely

47. Particle Shape:
--> flat, angular and irregularly shaped
particles settle more slowly than
smooth, rounded particle

48. Particle Density
--> denser particles settle faster
--> less dense particles settle more
slowly

49. Settling Rate and Settling
Time
--> Inverse relationship
--> faster rate indicates less settling
time
--> slower rate indicates more settling
time

50. Time Settling Time of Particles
Mass (g) (Size)
Settling Rate of Particles
(meters/sec.)
Rate
Mass (g)(Size)

51. Sorting of Sediments
--> velocity of transporting material
plays a major role in determining when
deposition of particles will occur
--> initiated by a reduction in velocity

52. Stream is moving at a velocity of 500 cm/sec
it is carrying all sized particles.
Slow down, drop
sediment load
Clay
Pebbles Silt
Sand

53. Horizontal sorting
 sorting with largest, densest and
roundest first and then farther out the
smallest, least dense and flattest
particles farther out (horizontal
arrangement)

54. Vertical sorting
(graded bedding)
particles are deposited in
layers with the largest,
densest and roundest
particles on the bottom and
then the smallest, least
dense and flattest particles
on top
Example: dropping a
mix of particles into water
(can be repetitive)

55. Deposition by streams:
Sandbars  shallow area in a stream due to
low water velocity
o frequently dredged to keep the stream
deep
Delta  deposits created when a stream
enters a larger body of water
o land around the mouth of the Mississippi
is a delta, New Orleans,
Mississippi delta is thousands of square miles

57. Deposition by Wind
 generally sorted by size and located
in arid climates
wind leaves behind larger sediments
creating

58. Sand dunes
 hills of wind blown deposits

59. Deposition by Gravity
 gravity pulls sediments toward the
Earth’s center, they are not sorted when
deposited by gravity, angular

60. Deposition by Glaciers
Adult person
 deposition occurs
when the glacier melts
leaving behind eroded
sediments
 unconsolidated and
unsorted
Glacial erratic  large
rocks that have been
transported by glacial ice

61. Two types of Glacial sediments:
1) unsorted sediments  deposited
directly by the glacier
2) sorted sediments  deposited
by the moving melt water of the glacier

62. New York and The Ice Ages
 NYS’ climate has changed over the last 2
million years causing 4 different ice ages
 Accumulation of snow and ice creates a
glacier that will then begin to move to lower
elevations due to its own weight
 When the climate warms again, glaciers
melt, releasing tremendous amounts of water
causing even more erosion

64. Types of Glaciers:
1) Alpine glaciers (valley glaciers) 
occur in mountain regions
2) Continental glaciers (ice sheets) 
large glaciers that start in colder regions
and move down slope
 this type of glacier produced most of NYS
glacial features

66. Evidence of Glaciation in NYS
U-shaped valleys

67. Evidence of Glaciation in NYS
glacial polish, rounded hills: bedrock that has
been smoothed by the scouring action of the
ice and collected sediments
striations grooves and scratches in the
bedrock, indicate the direction of flow
drumlins  small rounded mounds created
when a glacier goes over hills of
unconsolidated sediments

68. Evidence of Glaciation in NYS
moraines  unconsolidated, unsorted
sediments that were pushed forward by the
glacier as it advanced
o form Long Island and Cape Cod
o created the valley head moraine, which
allowed for the formation of the Finger Lakes
 outwash plan  area of sorted sediments
created by glacial melt water

74. The Oceans and Costal Processes
 Earth is 71%
covered by seawater
 Average depth 3
miles
 Most sediments
from land will be
eroded to the oceans
Edges of the oceans
are places of rapid
change caused by the
action of waves and
longshore currents.

75. Waves
water does not move forward with the
waves, but circulate transferring energy

76.  movement of waves and longshore
currents create many typical features
along the shoreline
humans love to live near the ocean, but
the rapid rate of erosion cause
destruction of property

77.  humans build structures to reduce the
damage created by waves
o breakwaters – shelter harbors, boats
jetties – build to keep sand from eroding
away from the beach

78. What is a Landscape?
Landscape  a region on Earth’s
surface in which physical features, such
as hills, valleys and streams are related
by a common origin
Topography  general shape of the
landscape

79.  landscape features are
determined by:
o climate
o bedrock
o geologic structures
o human activities

80. Landscape regions:
Mountains  greatest relief, often
igneous and metamorphic or
nonhorizontal sedimentary rocks
Example: Rockies, Adirondacks, Alps,
Himalayas

81. Landscape regions:
Plateau  relatively flat or rolling
uplands, underlain by flat sedimentary
bedrock
Example: Milford area, Grand
Canyon

82. Landscape regions:
Plains  little topographic relief, flat
low elevation
Example: Florida & Midwest

83. The Influence of Climate
 humid areas have more rounded
landscapes
arid areas have more sharp angles and
steeper slopes to the landscape

84. Moisture is important to the
rate of chemical weathering
 causing more rounded landscapes
 thicker soils
 promotes plant growth

85. Arid environments produce:
 greater amounts of physical
weathering
 thin soils
 deserts have the most rapid stream
erosion after a rainfall

86. Landscapes of the United States
abrupt changes in landscape is a result
of change in the bedrock

87. How do geologic Factors
influence the landscape?
 within the same climate landscape
regions can develop very differently
 hard minerals create rocks that are
very resistant to weathering and erosion
o creating cliffs or escarpments near
regions of less resistant rock
streams also follow areas of weaker,
softer rock

88. Landscapes affect drainage patterns

89. Landscapes of New York State
St. Lawrence/ Champlain Lowlands 
plains areas, predominantly layers of
sedimentary rocks

90. Appalachian Uplands (Allegheny Plateau)
 largest landscape region in NYS
o underlain by flat layers of
sedimentary rocks
o landscape have been uplifted
1000 of meters, which were later
eroded by streams (dissected plateau)
Finger lakes have been eroded out of
this landscape

91. Erie-Ontario Lowlands
 areas south of these lakes
o created by sediments left by
glacial meltwater
great soils for agricultural purposes

92. Adirondack Highlands
o only true mountain landscape in
NYS
o uplifted ancient metamorphic and
igneous rocks creating a dome
o very hard and resistant to
weathering
NYS highest mountain: Mount Marcy
(5240 feet)

95. Landscape vs. Age
Streams will continue to erode an area
to produce a wide flat valley and many
meanders in the stream