Table 3.1. Sediment Grade Scale (Brown 1950).
Approximate
Size
Sieve Mesh
Class
Openings
Per Inch
U.S.
Millimeters
Microns
Inches
Tyler
Standard
4000-2000
-----
-----
160-80
-----
-----
Very large boulders
2000-1000
-----
-----
80-40
-----
-----
Large boulders
1000-500
-----
-----
40-20
-----
-----
Medium boulders
500-250
-----
-----
20-10
-----
-----
Small boulders
250-130
-----
-----
10-5
-----
-----
Large cobbles
130-64
-----
-----
5-2.5
-----
-----
Small cobbles
64-32
-----
-----
2.5-1.3
-----
-----
Very coarse gravel
32-16
-----
-----
1.3-0.6
-----
-----
Coarse gravel
16-8
-----
-----
0.6-0.3
2 1/2
-----
Medium gravel
8-4
-----
-----
0.3-0.16
5
5
Fine gravel
4-2
-----
-----
0.16-0.08
9
10
Very fine gravel
2-1
2.00-1.00
2000-1000
-----
16
18
Very coarse sand
1-1/2
1.00-0.50
1000-500
-----
32
35
Coarse sand
1/2-1/4
0.50-0.25
500-250
-----
60
60
Medium sand
1/4-1/8
0.25-0.125
250-125
-----
115
120
Fine sand
1/8-1/16
01.25-0.062
125-62
-----
250
230
Very fine sand
1/16-1/32
0.062-0.031
62-31
-----
Coarse silt
1/32-1/64
0.031-0.016
31-16
-----
Medium silt
1/64-1/128
0.016-0.008
16-8
-----
Fine silt
1/128-1/256
0.008-0.004
8-4
-----
Very fine silt
1/256-1/512
0.004-0.0020
4-2
-----
Coarse clay
1/512-1/1024
0.0020-0.0010
2-1
-----
Medium clay
1/1024-1/2048
0.0010-0.0005
1-0.5
-----
Fine clay
1/2048-1/4096
0.0005-0.0002
0.5-0.24
-----
Very fine clay
3.3
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