Table 1. Sediment-size classification schemes. 



Unified Soils Classification 



Wentwortb Classification 



Size class 



Class limits 



Size class 



Class limits 





(mm) 





(mm) (phi) 









Boulder 



256.0 



-8 



Cobble 



76.0 





Cobble 











© 



64.0 



-6 



Coarse gravel 





> 



at 



o Pebble 









19.0 











Fine gravel 



4.76 





Granule 



4.0 



-2 



Coarse sand 





— 









2.0 





Very coarse sand 



2.0 



-1 



Medium sand 







Coarse sand 



1.0 











-d 



0.5 



1 





0.42 



§ Medium sand 











W 



0.25 



2 



Fine sand 



0.074 





Fine sand 

 Very fine sand 



0.125 



3 









— 



0.062 



4 



Silt or clay 





Silt 

 Clay 

 Colloid 



0.003 

 0.0002 



8 

 12 



