7908

• UCREFRP Catalog Number: 7908
• Author: Valdez, R. A. and R. J. Ryel.
• Title: Life History and Ecology of the Humpback Chub ‎(
• USFW Year: 1995.
• Copyright Material: NO

Table 1-3. Characteristics of geomorphic reaches. within the four study regions of the Colorado River in Grand Canyon. ::tl
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Extent of Name of Major Geologic Description Average Ratio Average Percentage of Bed -
Study Geomorphic Reach Geomorphic Units at River of Reach of Top Width to Channel Channel Composed of Bedrock ::tJ
Region Reach (river miles) Reach Levelb Width Mean Depth Width (feet) Slope and Boulders ~
0 1 0-11.3 Permian Section Kaibab Limestone Wide 11.7 280 .00099 42
T oroweap
Formation
Coconino
Sandstone
Hermit Shale
2 11.3-22.6 Supai Gorge Supai Group Narrow 7.7 210 0.0014 81
3 22.6-35.9 Redwall Gorge Redwall Limestone Narrow 9.0 220 0.0015 72
4 35.9-61.5c Lower Marble Canyon Muav Limestone Wide 19.1 350 0.0010 36
Bright Angel Shale
Tapeats Sandstone
5 61.5-77.4 Furnace Flats Tapeats Sandstone Wide 26.6 390 0.0021 30
Unkar Group
/I 6 77.4-117.8 Upper Granite Gorge Zoroaster Plutonic Narrow 7 190 0.0023 62
Complex
Trinity and Elves
Chasm Gneisses
Vishnu Schist
7 117.8-125.5 Aisles Tapeats Sandstone Narrow 11 230 0.0017 48
Vishnu Schist
8 125.5-139.9 Middle Granite Gorge Tapeats Sandstone Narrow 8.2 210 0.0020 68
Unkar Group
Vishnu Schist
9 139.9-159.9 Muav Gorge Muav Limestone Narrow 7.9 180 0.0012 78
III 10 159.9-213.9 Lower Canyon Basalt Wide 16.1 310 0.0013 32
Muav Limestone :i"
Bright Angel Shale .....
...
0
0-
11 213.9-226.0 Lower Granite Gorge Vishmu Schist Narrow 8.1 240 0.0016 58 c:
0
=:
0
"Adopted from Schmidt and Graf (1988, 1990), with slight variation in river miles (0.1 mil for Middle Granite Gorge, Muav Gorge, and Lower Canyon; Lower Granite Gorge :::J
was adjusted to 226.0 to correspond to the study area designation; features identified at 24,000 cfs. .
bFrom Hamblin and Rigby (1969). -"
CRegions 0 and I divide at RM 56.0; See Table 2-1. I
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