NYS Regents Earth Science
UNIT XII: Erosion, Deposition, and Landscapes
UNIT XII: EROSION, DEPOSITION, AND LANDSCAPES
NOTES PACKET
Picture: The Adirondack Mountains in
northern New York State. Most rocks
found here are metamorphic in origin and
over 1 billion years old. The Grenville
Orogeny was responsible
1 |for
P athe
g eobserved
changes recorded in the rocks.
NYS Regents Earth Science
UNIT XII: Erosion, Deposition, and Landscapes
After UNIT XII you should be able to:
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Understand how sediments are transported in a stream, use the Relationship of Transported Particle Size to Water Velocity
reference table chart, and recognize the characteristics of sediments that have been weathered in a stream
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Understand basic erosional and depositional features of a river
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Understand the relationship between particle shape and settling rate
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Understand how climate impacts landscapes near rivers
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Match topographical features with stream drainage patterns
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Recognize differences between glacial and river sediments
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Recognize differences between valleys eroded by glaciers and rivers
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Recognize common erosional and depositional features of glaciers
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Understand how erosion and deposition function within systems driven by wind, shoreline current, and mass movement and
recognize common features of these systems
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Recognize common landscape features of New York State and how they formed
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Be able to use the Generalized Landscape Regions of New York State map
UNIT XII vocabulary you should be able to use and understand:
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Erosion
Sediment
Gravity
Velocity
Particle
Transport
Boulders
Cobbles
Sand
Silt
Clay
Dissolved minerals
Deposition
Diameter
Morphology
Transect
River channel
Meander
Oxbow lake
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Accumulation
Unsorted sediments
Angular
Continental glacier
Ice sheet
Valley glacier
Alpine glacier
Abrasion
Striations
Polishing
Plucking
V-shaped valley
U-shaped valley
Finger lakes
Drumlins
Erratics
Kettle lakes
Eskers
Kames
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Moraines
Outwash plain
Cirque
Arete
Horn
Sand dunes
Long-shore drift
Mass movement
Landslide
Slump
Creep
Mudflow
Mountains
Fault-block mountains
Folded mountains
Landscape region
Plateau
Plain
Valleys
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Meander scar
Rounded
Sorted sediments
Suspended sediment
Settling rate
Delta
Alluvial fan
Downcutting
Stream drainage pattern
Orientation
Resistance
Weathering
Lowlands
Arid
Canyons
Humid
Topography
Glacier
Escarpment
Tying it together…
You now have had significant experience learning about the variety of ways rocks form, and some unique formations associated with the study
of plate tectonics. You are most familiar with what are known as uplifting forces. For example, the contribution of plate convergence to
volcanic mountain ranges. New crust is formed, old crust is recycled back into the Earth. The focus of this unit seeks to broaden your
understanding of leveling forces, those which contribute to transport of materials on the Earth’s surface in conjunction with your prior
knowledge of weathering.
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NYS Regents Earth Science
UNIT XII: Erosion, Deposition, and Landscapes
Our weathering unit taught us that rocks can be broken down by both physical and chemical means based on climate and bedrock
type. Understanding how Earth materials erode, becomes the next step in truly understanding the dynamic nature of landscapes.
Basic Principles of Erosion
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There are 5 distinct agents of erosion:
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Erosion in moving water varies greatly within a river, and between rivers. Lighter, less dense sediment is first to be transported by moving
water.
Transport of Sediments in Streams
Sediment transport is dependent on 2 variables:
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Describing Rock Particle Size
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Increasing Size
Rock Particles are categorized into 6 types:
*Dissolved minerals are also transported, although they are not visible
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NYS Regents Earth Science
UNIT XII: Erosion, Deposition, and Landscapes
Sediment Transport Chart
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If water velocity falls below that level, sediment is deposited on the bottom of
the river
Using the Chart
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Water Velocity and Stream Morphology
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Water velocity is not a constant along a river nor is it constant across a transect
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In other words, the stream is faster in some areas, slower in others
Water Velocity and Stream Morphology
Water, for the most part, flows in a straight line and will do so until redirected by the
stream channel. Water also over time dictates how the channel changes.
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Because this is true, rivers have different channel shapes at different locations
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In a straight line path, rivers are fastest in the middle, leaving a channel deepest
in the center
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Stream Meanders
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Over time, erosion at the outside of the bend causes the stream channel to drift. When the old channel is cut off, an
oxbow lake is formed.
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If the oxbow dries up, it becomes what is known as a meander scar
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NYS Regents Earth Science
UNIT XII: Erosion, Deposition, and Landscapes
Sorting of Sediments
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Faster moving water transports smaller sediments
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Therefore, a stream bottom will have larger particles on the bottom in faster
moving water and smaller particles on the bottom in slower moving water
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Shape and Density of Deposited Sediments
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When water velocity slows, the shape and density of sediment suspended is important when it comes
to the rate that the particles are deposited (settling rate)
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Using Principles of Deposition to Find Gold
You can pan for gold and find it in New York State streams, however a strange law prohibits you from keeping what
you find. Most gold in the state was transported by glaciers and ground down into fine dust and then concentrated in
streams, although nuggets are found on occasion.
Since gold is high in density, it settles first when water slows. When panning for gold, focus on cracks or joints in
bedrock within the stream, and on the inside of meanders.
Rivers Entering Lakes and Oceans
The deposition of sediments at the mouth of a river results in the formation of a delta or alluvial fan
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Stream Valley Shape
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NYS Regents Earth Science
UNIT XII: Erosion, Deposition, and Landscapes
Drainage Patterns
Looking at maps and examining rivers often tells us something about the rock strata beneath. Stream
drainage patterns are dictated by:
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Differences in Elevation
Higher elevations with steep slopes result in deep ‘V’ shaped valleys
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Drainage Topography in Arid Regions
Weathering in dry regions is generally a very slow process. The majority of weathering and erosion takes place in the
river channel.
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Drainage Topography in Humid Regions
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Common occurrence in NYS
Drainage Topography
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Mate these with an overhead pattern
Glaciers
New York State owes its many unique landforms to the presence of glaciers in the past. Evidence of repeated glacial events surrounds us in
western New York. Glaciers are responsible for both erosional and depositional features.
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NYS Regents Earth Science
UNIT XII: Erosion, Deposition, and Landscapes
Types of Glaciers
For our purposes, there are 2 types of glaciers that we are concerned with:
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Glacial Presence in NYS
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A massive glacier covered New York (most recently around 10,000 years ago), and it is important to
understand how it shaped landforms in the area
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The glacial movement map (with gray arrows) shows directional flow of the recent surges of ice
Glacial Weathering
Abrasion is the dominant form of weathering underneath a glacier
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This sediment may also result in the polishing of bedrock
Glaciers also pluck rock masses in their base and carry them along
Glacial Erosion
As glaciers erode a valley, they leave evidence of having been there
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Finger Lakes
Glacial erosion can leave behind a variety of observable features
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Satellite image (right) of the Finger Lakes region of New York State and the inferred glacial
movement that produced them (left)
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NYS Regents Earth Science
UNIT XII: Erosion, Deposition, and Landscapes
Drumlins
Elongated hills called drumlins are also found in areas that have undergone glaciation. The steeper end is on the
side where the glacier approached, the tapered end is the side the glacier was moving.
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Our Chimney Bluffs field trip was to one of the thousands of drumlins found in central and
western New York (image shows high lake level after glacial melt)
Erratics
Very large boulders that do not match local bedrock type (transported) or are found in awkward elevations or
places were likely transported there by a glacier.
This erratic is in Central Park sitting on top of striated bedrock, another piece of evidence for glaciation.
Kettle Lakes
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Devil’s Bathtub in Mendon Ponds Park is a kettle lake, one of a few that can be found there
Eskers
Long, winding hills of sediment deposited by streams beneath a glacier
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NYS Regents Earth Science
UNIT XII: Erosion, Deposition, and Landscapes
Kames
Rocky debris that is deposited in crevasses within a glacier to form a hill. A kame in Mendon Ponds Park is the highest
point in Monroe County.
Kames, eskers, and kettles can all be found in Mendon Ponds Park.
Moraines
Moraines are long hills that are composed of material that a glacier has pushed or pulled along
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The Valley Heads Moraine in the Finger Lakes Region represents the extent of the last glacial advance and
prevents southward drainage of the lakes
The Pinnacle Hills Range in Rochester – A series of hills caused by a sudden resurgence of ice depositing
sediment and home to many radio and telecommunication towers
Outwash Plain
An outwash plain is where streams flow out of the glacier as it melts. The plain is relatively flat with
sorted and rounded sediments due to abrasion in the streams.
Cirques, Aretes, Horns
All features found in mountainous areas (such as the Adirondack region) once covered by glaciers
Horn: Sharp point at mountain peak
Cirque: Bowl-shaped depression caused by abrasion
Arete: Sharp ridge carved out of the mountainside
Wind Erosion and Weathering
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NYS Regents Earth Science
UNIT XII: Erosion, Deposition, and Landscapes
Wind Deposition
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Wave Erosion and Weathering
Abrasion is the dominant form of weathering along beaches
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Long Shore Current
Long shore currents flow parallel to the beach. This flow steadily drags sediments along the shore in what
is called long shore drift.
Mass Movement
The final, though less substantial type of erosion is called mass movement.
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Landslide
Landslide is a commonly used term for the movement of a mass of bedrock or loose soil and rock down the slope of a hill, mountain or cliff.
Creep
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Slump
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Blocks of land that have tilted and moved downhill along a surface that curves into the slope
Mudslides/Flows
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NYS Regents Earth Science
UNIT XII: Erosion, Deposition, and Landscapes
Weathering, erosion, deposition, plate tectonics, folding and faulting all contribute to the beautiful landscapes around us, many of which can
be found in New York.
Landscapes Features of NYS
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Mountains
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NYS Example: Mount Marcy (Adirondack Mountains)
The Adirondack Mountains are part of an area which has been uplifted and domed upward
and continues to do so. They are not volcanic in origin and are comprised mostly of metamorphic and intrusive igneous rocks.
Other Types of Mountains
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Folded Mountains form when compression occurs typically during a tectonic collision
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Fault Block Mountains occur when faults (lines of breakage) allow rock on either side to
move up or down relative to the opposite side
Plateau
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NYS Example: Allegheny Plateau
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NYS Regents Earth Science
UNIT XII: Erosion, Deposition, and Landscapes
Plains
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Example: Erie-Ontario Lowlands, City of Rochester
Valleys
Valleys can be formed from erosion by rivers, glaciers, in between folds in bedrock, or where a fault block has fallen down.
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Ridges
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A chain of mountains or hills that form a crest for some distance
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Folded bedrock in Pennsylvania has formed ridges along the folds
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Ridges are sometimes lines of resistant bedrock
Escarpments
Escarpments are long cliffs formed by erosion or faulting
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Land is relatively flat on either side
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NYS Landscape Map
Use this map to identify major landscape regions in NYS
For example: Which landscape region is Rochester located in?
Answer:__________________________
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