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Geological Survey Bulletin 1508
The Geologic Story of Colorado National Monument
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TRIPS THROUGH AND AROUND
THE MONUMENT(continued)
From the East Entrance to Grand Junction
SOUTH CAMP ROAD SHORTCUT |
THREE FOURTHS OF A MILE beyond
the checking station, South Camp Road turns left and joins South
Broadway 2-1/2 miles to the northwest. This provides a fine shortcut for
persons desirous of travelling back northwestward through The Redlands
to regain the West Entrance of the Monument. The intersection of South
Camp Road and South Broadway, a key point on the trip "From Grand
Junction through The Redlands to the West Entrance of the Monument," is
noted on page 89.
But let us continue our 3-mile return trip to Grand
Junction, in order to point out several things of interest along
Monument Road in the lower part of No Thoroughfare Canyon. As the canyon
narrows just beyond the road intersection, we see on both sides colorful
badlands of the Morrison Formation capped by the rusty looking basal
sandstones of the Burro Canyon Formation. Behind the building on the
right just before the road curves to the left is an artesian well 575
feet deep that taps both the Entrada Sandstone and a sandstone lens in
the Morrison Formation35.
35Lohman, 1965a, p. 106. well 33.
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33 GAP IN ROCK RECORD |
About 2-1/2 miles below the checking station,
we pass on the left the basal sandstone of the Burro Canyon
Formation resting on the Morrison Formation, as shown in the
lower left of figure 24. Just beyond we may look up the hill to the left
and see the 40-foot basal conglomerate of the Dakota Sandstone resting
unconformably on an old erosion surface atop the Burro Canyon
Formation.
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FLOOD DAMAGE |
Just before we reach the T-intersection with
the eastern segment of South Broadway we may still see on the right some of
the destruction caused by a devastating flood that roared
down No Thoroughfare and other canyons on September 7,
1978, as a result of what was termed the worst cloudburst to
hit Glade Park, the Monument, and the Grand Valley since
1958. A house on the flood plain just above the bridge was
badly damaged and was filled with 4 feet of mud, and the
Monument Road bridge across No Thoroughfare Canyon
nearest the intersection was washed out, necessitating the
rerouting of traffic to and from the East Entrance of the
Monument. Moralnever build a house or even
pitch a tent in a dry wash or arroyo in desert regions! Incidently,
indirect measurements by engineers of the U.S. Geological Survey
indicated a discharge of 9,290 cfs just above the washed out bridge in No
Thoroughfare Canyon, and 2,980 cfs in Red Canyon beneath the Broadway
bridge.
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SOUTH BROADWAY |
Inasmuch as the bridge on Monument Road has
long since been rebuilt, we will cross it, turn right on South
Broadway at the T-intersection, cross the Redlands Power Canal
(p. 88), and join Colorado Highway 340 at the traffic light; thus, we
complete a round trip "From Grand Junction through The Redlands to the
West Entrance of the Monument,"' "Through the Monument from West to East
Entrances," and "From the East Entrance to Grand Junction."
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bul/1508/sec12d.htm
Last Updated: 8-Jan-2007
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