USGS Wentworth Grain Size Chart
USGS Wentworth Grain Size Chart
USGS Wentworth Grain Size Chart
Decimal inches
SIEVE Settling
Fractional mm
Number
Intermediate diameters
COVERSION
φ = log 2 (d in mm) SIZES of grains Velocity Velocity
of natural grains
1µm = 0.001mm (after
and
Wentworth,1922) per mg (Quartz, for traction
φ
(U.S. Standard)
20°C) cm/sec
mm
ASTM No.
Mesh No.
(Gibbs, 1971)
(modified from
Hjuistrom,1939)
-8
Tyler
256 10.1"
(Nevin,1946)
Spheres
Crushed
spheres
Natural
Quartz
sand
200 BOULDERS
> -8φ )
(_
-7 128 5.04"
cm/sec
100 COBBLES 200
1m
above
-6 64.0 2.52" 2 1/2" bottom
53.9 2.12" 2"
50 very
45.3
40 coarse 150
33.1 1 1/2" 1 1/2"
-5 30 32.0 1.26" 1 1/4"
26.9 1.06" 1.05"
22.6 coarse 50
20 17.0 3/4" 100
.742"
-4
PEBBLES
.4 .420 40 35 6
.354 medium 45 42 .42 15 13 5 4
.3 .297 50 48 4
2 .250 1/4 60 60 .30 43 35 3 3
.2 .210 70 65 20 26
.177 fine 80 80 .215 120 91 2 2
.149 100 100 Minimum
3 .125 1/8 120 115 .155 350 240 (Inman,1949)
1
.1 .105 very 140 150 1.0
.088 fine 170 170 .115 1000 580
.074 200 200 0.5 0.5
4 .062 1/16 230 250 .080 2900 1700 0.329
.05 .053 270 270
Note: The relation between the beginning
depends on the height above the bottom
.04
of traction transport and the velocity
medium
.02
Stokes Law (R = 6πrηv)
Note: Applies to subangular to
other factors.
fine 0.01
.01
7 .008 1/128 0.0057
( in mm )
very
.005 fine
8 .004 .004 1/256
Clay/Silt
0.0014
0.001
.003 boundary
for mineral
CLAY
analysis
9 .002 .002 1/512 0.00036
0.0001
10 .001 .001 1/1024