Udden-Wentworth scale

It needs to be stated in this context, that, in order to compare the quantitative reports of published grain sizes, the international literature does not draw the line between silt and clay at 0.0039 mm - as the U S standard and the Udden-Wentworth scale does (Table 1.3), or the French AFNOR-norm, but sets the limit at 0.002 mm, a value very often found in German literatnre and complying with the DlN-standards. To add to further diversity, modern pnblications from Russia mark the silt-clay transition at a grain size of 0.01 mm (e.g. Lisitzin 1996). 

Table 13.1 Udden-Wentworth Grain-Size Scale.

Table 1.3 Grain-size scales and textural classification following the Udden-Wentworth US Standard. The phi values (i>) according to Krumhein (1934) and Krumbein and Graybill (1965) ( ) = - logj d/d, where d is the standard grain diameter (i.e. 1 mm).

---