Today

1
Today

• Mass Wasting (end of Ch. 15)
• Start Fluvial Processes (Ch. 16)
• Start Lab Three (due in two weeks)
• FIELD TRIP 3 IS NOW FRIDAY, APRIL 17

2
mass wasting (end of Ch. 15)

• the movement in which bedrock, debris, regolith,
  and/or soil moves down a slope a short distance
• gravity dominates
• requires a trigger

3
mass wasting

• Question What keeps Austin Bluffs up there?
• Answer
• RESISTING FORCES
• rock strength
• rock structure

4
mass wasting
United States landslide incidence and
susceptibility map.National Atlas of the United
States
http//nationalatlas.gov/articles/geology/a_landsl
ide.html
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angle of repose

• angle of repose the steepest angle at which
  debris remains stable
• a balance between gravity and resistance
• talus typically between 30 to 37
• dry sand typically between 28 to 30

32
6
angle of repose
http//uregina.ca/sauchyn/geog323/324.jpg
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angle of repose
http//taos-telecommunity.org/epow/EPOW-Archive/ar
chive_2004/EPOW-040719.htm
http//www.icsi.berkeley.edu/dbailey/gallery/
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mass wasting controls

• gravity
• water/wetness
• water lubricates (reduces resistance)
• water adds weight
• frozen groundwater (permafrost)
• steep slopes
• undermining at base of slope
• piling weight on top of slope
• vegetation removal
• plants/roots add stability by protection against
  erosion
• clay
• clay absorbs water and is SLICK!

http//www.spokane.wsu.edu/academic/design/resourc
eroom/clay.htm
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mass wasting triggers

• triggers
• heavy rain
• oversteepening
• deforestation
• vibrations
• volcanic eruptions
• meteor impact
• nuclear testing
• some sort of thresholdis breached

http//pubs.usgs.gov/fs/2003/fs014-03/
The 7.9 Denali FaultEarthquake of 2002
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mass wasting types

• fall
• fastest a rock falls and becomes talus
• slide
• fast with/without water regolith and sometimes
  bedrock too
• slow slumping rotational slide
• flow
• slow with water earthflow mudflow debris flow
• creep
• very slow wet/dry freeze/thaw solifluction

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mass wasting types

• fall
• fastest a rock falls and becomes talus

http//atlas.nrcan.gc.ca/site/english/maps/environ
ment/naturalhazards/landslides/
http//www.physci.mc.maricopa.edu/Geology/FieldTri
ps/ColoradoRiver/
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mass wasting types

• fall
• fastest a rock falls and becomes talus

http//gees.usc.edu/GEER/
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mass wasting types

• fall
• fastest a rock falls and becomes talus

On Tuesday, May 23, 2006 at 500pm on the Wall
Street section of the Navajo Loop Trail there was
a significant rock fall. The rock fall was caused
by erosion and weathering, which have shaped
Bryce Canyon into what visitors see today. The
primary weathering force at Bryce Canyon is frost
wedging. Here we experience over 200 freeze/thaw
cycles each year.
Image from http//www.nps.gov/brca/parknews/navaj
o-loop-trail-rock-fall.htm
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mass wasting types

• fall
• fastest a rock falls and becomes talus

1982 rockfall in Yosemite.
http//virtual.yosemite.cc.ca.us/ghayes/1982.htm
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mass wasting types

• fall
• fastest a rock falls and becomes talus

Image from http//geology.com/articles/yosemite-r
ockfall.shtml
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mass wasting types

• fall
• fastest a rock falls and becomes talus

Image from http//landslides.usgs.gov/learning/ph
otos/images/colorado__u.s._/glenwood_canyon__co__2
003/fig1.jpg
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mass wasting types

• fall
• fastest a rock falls and becomes talus

http//landslides.usgs.gov/learning/photos/images/
more_usa/various_landslides_throughout_the_united_
states/cn_landslide.jpg
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mass wasting types

• slide
• fast with/without water regolith and sometimes
  bedrock too
• slow slumping rotational slide

scarps
slide mass
toe
Youtube link
news link
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mass wasting types

• slide
• fast with/without water regolith and sometimes
  bedrock too
• slow slumping rotational slide

fast slide
slow slide
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mass wasting types

• slide

http//hkss.cedd.gov.hk/hkss/eng/slopeinfo/images/
PoShanLandslide.jpg
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mass wasting types

• flow
• slow with water earthflow mudflow debris flow

Youtube link
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mass wasting types

• flow
• slow with water earthflow mudflow debris flow

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http//almandine.geol.wwu.edu/dave/courses/2003/s
pring/101/lectures/1320Mass20Wasting.ppt373,26,
Slide 26
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(No Transcript)
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(No Transcript)
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mass wasting types

• creep
• very slow wet/dry freeze/thaw solifluction

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mass wasting types

• creep
• very slow wet/dry freeze/thaw solifluction

http//almandine.geol.wwu.edu/dave/courses/2003/s
pring/101/lectures/1320Mass20Wasting.ppt368,18,
Creep
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mass wasting types

• creep
• very slow wet/dry freeze/thaw solifluction

http//landslides.usgs.gov/learning/photos/images/
more_usa/various_landslides_throughout_the_united_
states/creep2.jpg
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mass wasting types

• creep
• very slow wet/dry freeze/thaw solifluction

waterlogged sediment moves over an impermeable
surface
http//www.fao.org
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mass wasting types

• creep
• very slow wet/dry freeze/thaw solifluction

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For more info on mass wasting

• http//www.usgs.gov/science/science.php?term1736
  typetheme

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Next Chapter 16

• The Fluvial Processes

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Alaganic Slough, Cordova, Alaska (photo by Al
Vogt)
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Hominy Pond Dam, Columbia, MO (photo by Al Vogt)
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The New Hominy Wetlands, Columbia, MO (photo by
Al Vogt)
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Fluvial Processes (Ch. 16)

• Basic concepts
• fluvial facts
• overland flow and streamflow
• drainage basin/watershed
• drainage divides
• stream orders
• transportation
• deposition
• role of floods

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basic concepts fluvial facts

• Fluvial (from L. fluvius river)
• Globally, running water dominates all other
  landform evolution processes
• Running water moves 85 to 90 (or more) of the
  total sediment, glaciers 7, groundwater and
  waves about 1, wind less than 1.

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basic concepts fluvial facts

• Running water erodes and deposits
• 2 4 of potential energy in moving water is
  converted to the mechanical work of erosion (the
  vast majority of energy is lost to friction and
  turbulence)
• Globally, a full 1/3 of Earths land surface has
  NO runoff to the oceans!

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basic concepts overland flow and streamflow

• ? overland flow unchanneled downslope movement
  of surface water
• ? streamflow channeled movement of water along
  a valley
• bottom

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basic concepts valleys and interfluves

• ? valleys the portions of the landscape in which
  a drainage system is clearly established
• ? interfluves higher land above the valley sides
  that separates adjacent valleys

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basic concepts base level

• base level
• the elevation at which a stream ends, by entering
  a large standing body of water, such as a lake or
  ocean
• ocean is ultimate base level
• local and temporary base levels exist as well

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basic concepts aquifer

• aquifer - a body of rock or regolith
  sufficiently permeable to store and transport
  significant quantities of groundwater (USGS).

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basic concepts drainage basin

• drainage basin (or watershed) - an area of land
  that drains all the streams and rainfall to a
  common outlet such as the outflow of a reservoir,
  mouth of a bay, or any point along a stream
  channel (USGS).

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basic concepts drainage basin
http//water.usgs.gov/wsc/map_index.html
There are 18 USGS Water Resource Regions in the
US
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basic concepts drainage basin
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basic concepts drainage basin
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basic concepts drainage basin
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basic concepts drainage basin
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basic concepts drainage basin
Creeks within the Fountain Creek Watershed
contribute about 15 of the drinking water for
Colorado Springs and are a source of irrigation
for over 100 farms and ranches. 85 of Colorado
Springs' water is pumped from west of the
Continental Divide, and after use, this water is
treated and discharged into Fountain Creek.
Over 90 of Pueblo's 100-year floodplain is
developed and includes residential, commercial,
industrial and public properties. Parts of
Pueblo's downtown business district lie directly
within the historic floodplain of Fountain Creek.
Pueblo's flooding history includes devastating
floods in 1921, 1935 and 1965.
Fountain Creek Watershed927 mi. 2
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Get involved!

• Citizen groups for Fountain Creek Watershed
• S.O.S. Save Our Shoulders
• Fountain Creek Watershed Technical Committee
• Cheyenne Creek Conservation Club _at_ Canon
  Elementary School
• Environmental orgs for Fountain Creek Watershed
• Colorado Springs Utilities
• Fountain Creek Crown Jewell Project
• Pike, San Isabel National Forests, Cimarron and
  Comanche National Grasslands
• Pueblo Dam

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basic concepts drainage divide

• ? drainage divide marks the edge of two adjacent
  drainage basins

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basic concepts drainage divide

• Question What is the Continental (or Great)
  Divide?

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basic concepts drainage divide
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basic concepts stream order

• 1st order no tributaries
• 2nd Order when two1st order streams unite
• 3rd order when two 2nd order streams unite

http//www.stormwatercenter.net/
Stream order is a method for classifying the
relative location of a stream within the larger
river system.
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basic concepts stream order
http//www.fgmorph.com/
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basic concepts stream order
http//www.fgmorph.com/
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NEXT erosion and deposition

• overland flow
• streamflow
• transportation of material
• deposition of material
• the role of floods

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erosion and deposition erosion by overland flow

• splash erosion erosion caused by collision of
  raindrops w/ ground
• sheet erosion caused by water moving downslope
  as a thin sheet

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erosion and deposition stream flow

• rills and rill erosion the break up of the sheet
  flow into many tiny channels
• gullies and gully erosion caused as rills
  coalesce into fewer larger channels

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erosion and deposition transportation of material

• stream load
• -- dissolved load
• (salts)
• -- suspended load
• (silt/clay)
• -- bedload
• (sand/gravel)

most material is transported via suspended load
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erosion and deposition transportation of material

• How does bedload travel?
• -- saltation
• leaping/bouncing/jumping
• -- traction
• rolling/sliding/dragging

TRANSPORTATION ANIMATION
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erosion and deposition deposition of alluvium

• deposition occurs as either flow speed or water
  volume decreases
• alluvium any stream-deposited debris
• -- sorted by size
• -- smoothed rounded

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• Question How do rivers sort rocks by size?

example of sorting at entire river scale
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• Question How do rivers sort rocks by size?

example of sorting at sandbar scale
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erosion and depositionthe role of floods

• floods may not occur frequently BUT remember
• geologic time
• streams have erratic discharge (flow volume)
  regimes
• floods can last months or minutes
• brief events can do 100s of years worth of
  erosion
• The epic work of streams the carving of great
  valleys, the forming of vast floodplains is
  primarily accomplished by flood events (pg. 486)

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NEXT fluvial processes and patterns

• CFS
• hydrographs
• recurrence intervals
• stream flow regimes
• water behavior
• channel patterns
• drainage patterns
• shaping of valleys

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cubic feet per second (CFS)
This is about 40 CFS

• Big T was about31,000 CFS
• Today, FountainCreek is at about100 CFS
• Mississippi R.ave. is 450,000 CFS

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http//waterdata.usgs.gov
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http//waterdata.usgs.gov