9331

• UCREFRP Catalog Number: 9331
• Author: Allred, T. M. and J. C. Schmidt
• Title: Channel narrowing by vertical accretion along the Green River near Green River, Utah
• USFW Year: 1999
• USFW - Doc Type: Geological Society of American Bulletin
• Copyright Material: YES

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TABLE 5. PARTICLE SIZE DISTRIBUTION OF THE VERTICALLY ACCRETED DEPOSIT ON THE RIGHT BANK ....
AT THE PRESENTCABLEWAY
Elevation Sieve analysis Organic carbon Visual accumulation tube analysis Comments
(m) Sand" Siltt ClayS (%) Percent ot sample with fall diameter finer than indicated size
(%) (%) (%) (mm)
0.175 0.125 0.088 0.0625
4.05 64 28 8 99 96 83 52
3.90 77 16 7 100 93 71 35
3.80 24 61 16 100 98 93 82
3.70 49 48 3 0.31 100 99 92 70
3.49 36 49 15 100 97 88 71
3.42 22 65 13 100 100 98 89
3.34 32 57 12 0.87 100 99 97 84
3.24 16 <-84 -> 3.83 100 97 92 86 Upper organic layer
3.20 20 62 18 100 99 96 87
3.16 39 45 17 1.26 100 96 85 68 Lower organic layer
3.09 70 22 8 0.17 100 94 73 40
2.94 58 29 13 100 97 82 55
2.78 49 37 14 0.51 100 97 84 61
2.63 48 40 12 100 99 88 65
2.48 1 79 20 <- Insufficient quantity of sand for analysis ->
2.33 47 44 9 100 99 93 73
"Greater than 0.0625 mm.
tBetween 0.0625 mm and 0.002 mm.
~Less than 0.002 mm.

1400 C
W 1200
(!)
a:~ 1000
<c.!!1 800 ~
J:~ ;
uS 600
en Position of saltcedar
5 400 / in the deposit
200
0
5
B 1200
4 900
Z 700
0
I- 3 500 Cil
<( ;:;--
> S
W 250
..J
w- 2
>-s
a: 100
<(
a: 50
I- 1
m
a:
<(
0
-1 1971 1976 1981 1986 1991 45 35 25
YEAR POSITION ON CABLEWAY
Saltcedar colonize bar (m)

Figure 14. Detailed history of the formation of an inset floodplain deposit. (A) Vertical accretion of the inset floodplain over time. Blue shaded
regions indicate periods of inundation. Data points marked with triangles are from U.S. Geological Survey (USGS) discharge measurement data;
point marked with a star was estimated from the stratigraphy ofthe excavated area (shown by dashed box). (B) Plots of the nearly horizontal bar
surface as it accreted vertically, taken from USGS discharge measurement data. Also shown is the approximate vertical position of the saItcedar
that were excavated from the deposit. (C) Plot of discharge for the same time period shown in A. Note that flood magnitudes that inundated the
bar in 1960 are of insufficient stage to inundate the bar in 1976. Also note the incremental nature of the bar building process, the rapid rate of ac-
cretion, and that measurable accretion did not occur during all periods of inundation.

1770

Geological Society of America Bulletin, December 1999