Table 1. Grain-size scales — soil classification (modified from U.S. 

 Army, Corps of Engineers, Coastal Engineering Research 

 Center, 1977'*). 



Unified Soils 

 Classification 



ASTM 

 Mesh 



mm 

 Size 



Phi 

 Value 



Wentworth 

 Classification 



COBBLE 



^////M^^^^^^^ 



COARSE 

 GRAVEL 



FINE GRAVEL 



medium 







4^^^'4"^4.>6^-^'.'»^ 



coarse 



fine 



SILT 



CLAY 



256.0 -8.0 



^?64TO^r-6!0 



4^m%k%%4%'i9'.-b-^4^-4:?5^ 



^^ 5 .i^' ■■.-' ^4.0f^^-2.0 



^ler^ .^ :It:o> rpyp . ^:; 



VAy^mmi :^ ^•-••o 



-N 



10: 



^ 



P"'--' -tTV ITo'..;. 



,Mm^mM.i-m 



iSO 10.25 To" 



I-">I20. .,.0.I2S 3.0 



^206^0:^74^3:75'^ 





.,230; 0.062 M.O 



^^E2iM9-M 



10:0024 J 2.0 



:> 

 :> 



BOULDER 



COBBLE 



PEBBLE 



GRAVEL 



very 

 coarse 



coarse 



medium 



fine 



very fine 



s 



A 

 N 

 



SILT 



CLAY 



COLLOID 



*U.S. ARMY, CORPS OF ENGINEERS, COASTAL ENGINEERING RESEARCH CENTER, 

 op. cit., p. 7. 



