Upload
mignon
View
53
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Wind erosion & Deposition. WED V15. What is wind?. Wind the horizontal flow of air. It is caused by horizontal differences in pressure which result from the unequal heating of Earth’s surface - PowerPoint PPT Presentation
Citation preview
WED V15
WIND EROSION & DEPOSITION
WHAT IS WIND?
Wind the horizontal flow of air. It is caused by horizontal
differences in pressure which result from the unequal heating of Earth’s surface
http://www.classzone.com/books/earth_science/terc/content/visualizations/es1903/es1903page01.cfm?chapter_no=visualization
FEATURES CAUSED BY WIND
Ripples and dunes
Windward side is gentle
Leeward side is steep
http://geology.wr.usgs.gov/parks/coast/dunes/index.html
FOR DUNES & RIPPLES TO FORM YOU NEED…
Wind Dry sand Wind break (drift wood, dead
bird, plant, etc.)
DUNES
http://geology.wr.usgs.gov/parks/coast/dunes/index.html
DUNE FORMATION steady supply of sand, wind, and a wind break
beaches and at the base of mountains in dry regions.
Wet sand will not blow around to form ripples and dunes
Mesquite Flats, Death Valley, CAhttp://www.uoregon.edu/~millerm/sanddunes.html
GRASSES ON THE DUNES HELP STABILIZE THE BEACH
http://geology.wr.usgs.gov/parks/coast/dunes/index.html
http://www.nps.gov/archive/grsa/resources/images/photos/dune_pattern03.jpg
Wind blows sand and makes ripples Once sand begins to pile up, ripples and dunes can form.
RIPPLES GROW INTO DUNES WITH INCREASE OF WIND
AND SAND INPUT
http://geology.wr.usgs.gov/parks/coast/dunes/index.html
The collapsing sand comes to rest when it reaches just the right steepness- 30 to 34 degrees, or angle of repose- to keep the dune stable.
http://geology.wr.usgs.gov/parks/coast/dunes/index.html
SAND BLOWING OFF A DUNE
http://www.uoregon.edu/~millerm/depenv.html
ANIMATION
http://highered.mcgraw-hill.com/sites/0072402466/student_view0/chapter13/animations_and_movies.html#
MIGRATION sand inches up the windward side to the
dune crest
then slips down the dune's slip face
the dune to inches forward, migrating in the direction the wind blows
this leaves its mark on the internal structure of the dune.
http://geology.wr.usgs.gov/parks/coast/dunes/index.html
CROSS-BEDDING PRESERVED IN SANDSTONE
http://www.wwnorton.com/college/geo/egeo/flash/5_1.swf
http://geology.wr.usgs.gov/parks/coast/dunes/index.html
NAVAJO SANDSTONE
CROSS BEDDING IN THE NAVAJO SANDSTONE
ARCHES NATIONAL PARK
STAR DUNE COMPLEX
The wind blows from different directions throughout the year.
http://www.nps.gov/archive/grsa/resources/images/photos/dunes_cristos03.jpg
MAIN DUNE FIELD AT WHITE SANDS NATIONAL MONUMENT
http://www.nps.gov/archive/grsa/resources/images/photos/landscape_sw02jpg.jpg
http://www.nps.gov/archive/grsa/resources/photos_landscape.htm
http://www.nps.gov/archive/grsa/resources/photos_landscape.htm
http://www.nps.gov/archive/grsa/resources/photos_landscape.htm
VENTIFACTS
http://earthsci.org/education/teacher/basicgeol/windes/ventifact.gif
FEATURES CAUSED BY WIND
Ventifacts rocks flattened and smoothed
by wind abrasion
FEATURES CAUSED BY WIND
Desert pavement
Surface where wind has blown away the smaller sediment
Deflation: removal of silt, sand, and clay by wind
DESERT PAVEMENT
http://media-2.web.britannica.com/eb-media/28/10728-004-83F5D724.jpg
http://www.uwgb.edu/DutchS/geophoto/aeolian/DPAVMT1.jpg
http://www.goldengatephoto.com/jpeg/99-29-7.jpg
EVIDENCE OF WIND ABRASION: FROSTED GRAINS
http://en.wikipedia.org/wiki/File:WhiteSandsGypsum.jpg
LOESS Wind-blown silt
deposits
Often forms thick layers as wind deposits small particles swept from glacial outwash plains
http://en.wikipedia.org/wiki/File:LoessVicksburg.jpg
“When the Yellow River runs clear”
Means the same as
“When Pigs fly”
http://upload.wikimedia.org/wikipedia/commons/e/ea/Hukou_Waterfall.jpg
http://en.wikipedia.org/wiki/File:Loess_landscape_china.jpg
The photograph below shows a sand dune that formed in a coastal area.
This sand dune was most likely formed by(1) water flowing from the left(2) water flowing from the right(3) wind blowing from the left(4) wind blowing from the right
DRAW THE SAND