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L58 Rock Fins. Arches National Park, Utah, USA
Position:
N38° 47.440
W109° 35.838
Elevation:
5202' / 1585m
Image format:
MF 35mm
ROCK FINS. ARCHES NATIONAL PARK. UTAH, USA
These rock 'fins' in America's Arches National Park are the key
to understanding some important features of the landscape in this
region. Here's why:
Take a candy bar and try to bend it. Some will break clean in
two; some will 'stretch' or flow on the outside of the bend until
you tear the bar in two. If you just apply the pressure but stop
before you break the bar, what you will have done is to make STRESS
FRACTURES across the candy bar.
In this part of Utah, the rocks have been stressed in much the
same way. The surface rocks have been put under pressure and flexed
or mildly bent. Stress fractures have developed. Rain, frost and
wind (even tree roots) have got to work in the cracks and made
them wider.
That's what this image shows. Stress fractures, opened out by
processes of WEATHERING and EROSION. Now look at images L59 through L61 to see what 'happens' next. Images L58 through L62
are in sequence and should be viewed as a series.
Less detail
Image Trail:
L59 Rock Fin (II). Arches National Park. Utah, USA
L60 Landscape Arch. Arches National Park. Utah, USA
L61 An evolving Arch. Arches National Park. Utah, USA
L62 The End & the Beginning of Arches. Arches National Park. Utah,
USA
L70 Window Arch. Moab, Utah, USA
Links:
www.aqd.nps.gov/grd/parks/arch/index.htm (site includes some very good sketches showing the development
of Natural Arches)
http://www.nps.gov/seug/resource/geology/geology.htm
http://geography.com.sg/weathering/index.html
http://geography.com.sg/rivers/index.html
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