TODAY
• Get out your ESRT and a piece of paper
• The following questions are from your
ESRT.
• You’ll have a minute per question…
Question 1
• What are 2 examples of weathering?
Question 2
• What is the difference between soil and
dirt?
Question 3
• What is the P-wave travel time for 4000
km?
Question 4
• What layer of the earth has a greater
temperature than melting point?
Answers
• Two examples
– Abrasion, Frost action
• Soil and Dirt?
– Darker, particle size
• P-wave travel time for 4000 km?
– 00:07:00
• What layer of the earth has a greater
temperature than melting point?
– Outer Core
Erosion
Movement of weathered particles
Vocab
•
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Agents of erosion
Suspension
Saltation
Creep
Angle of repose
Mass wasting
Weathering Vs Erosion
• Weathering
– Breaking down of
rocks and other
particles into smaller
pieces
TALUS ?
• Erosion
– Transport of the
weathered particles.
Agents of Erosion
1) Gravity
2) Water
3) Wind
4) Ice
Water
• Water when driven by gravity can be
very powerful.
• Think of the drainage ditch after it rains
– does the water flow fast? Is it clean?
Wind
•
3 things to know.
1. Suspension – Stuff in the air
2. Saltation – Bouncing
3. Creep – Rolling on the ground
Dust bowl, Causes???
Ice
• Glaciers move ice
down a slope
picking up
sediments along
the way.
• Long Island is
simply glacial
Poop!
Gravity
• Gravity drives all erosion, but one form
more important to know is mass
movements.
• This is when the soil fails and falls or
slides down a slope.
• Angle Of Repose
– Angle where material
stays on surface!
Mass movements
• Slump
– This is when the land
slides down equally.
• Slide
– This is when the land
slides down not
equally.
• Fall- avalanche
– The land falls
• Flow
– The land is liquefied
and flows down.
Things that will increase mass
movements
1. Change water content
2. Change slope
3. Change mass
4. Change vegetation
5. Change human activity
Tully Landslide ‘91
¼ mile
http://pubs.usgs.gov/of/1994/ofr-94-0615/tvstudy.htm
Tully Landslide
• April 30, 1993. After a long winter full of
rain and snow. The saturated land gave
away and began to flow down the hill.
Deposition
What is this?
What controls this?
Deposition
• This is like going to the bank
geologically.
• Weathering breaks the rocks up
• Erosion moves the particles.
• Deposition leaves the particles on the
ground.
Factors
• Particle Size
– How big the sediments are.
• Shape
– Round or flat
• Density
– Weight and composition
• Settling rates
– How fast things settle
Sorting Vs Unsorted
• ESRT page
• How to find
sediment size.
• How to find
Speed.
Ways to deposit
• Glaciers
– Sorted or Unsorted
• Streams (Water)
– Sorted or Unsorted
• Wind
– Sorted or Unsorted
• Mass movements (gravity)
– Sorted or Unsorted
Gravity
• Gravity alone does not sort sediment
• Landslides are the main form of gravity
deposition.
• Why are sediments
unsorted?
Glaciers
• Glaciers leave sediment unsorted.
• Like gravity
Land slides
• What moves the
glacier?
Water
• Streams, Rivers deposit sediment in
sorted layers.
• Why are sediments
sorted?
Wind
• Wind like water sorts sediments.
• Why are sediments sorted?
Wind
• Wind like water sorts sediments.
• Why are sediments sorted?