GRADE AND CLASS TERMS FOR CLASTIC SEDIMENTS 391 



sediments tested was assigned to a suitable name differing only in 

 added exactness from that used in the original description. In 

 the table below are given nine of these analyses showing the 



Table of Mechanical Analyses by J. A. Udden* Showing the Sediment Names 

 Appropriate to the Classification of This Paper 



Diameter in Millimeters 



No. 7st 

 Gravel f 



No. 9 

 Sandy Gravel 



No. 18 

 Gravelly Sand 



No. 16 

 Sand 



No. 68 

 Silty Sand 



64-32. 

 32-16. 

 16-8. . 

 8-4... 

 4-2 .. . 



I-1/2 



1/2-1/4 



1/4-1/8.... 

 1/8-1/16. . . 

 1/16-1/32. . 

 1/32-1/64. . 

 1/64-1/128. . 

 I /l 28-1 7256. 



3-3 

 65-9 

 26.0 



•3 



. 2 



•7 

 •3 



14.0 



13.2 



20.0 



14.4 



II. 4 



18.2 



5-6 



2.6 



. 2 



6.1 



7-4 



3.6 



7.2 



36.8 



37-4 

 I. 2 



1-7 

 24.4 

 49.2 



8-3 



14.8 



1 .0 



• 4 



•3 



7.2 

 17.9 

 48.7 



8.4 

 13.2 



3-2 

 •7 



* J. A. Udden, loc. cit. 



t The numbers are those used by Udden in describing these sediments. The names are applied 

 by the author of this paper according to the terminology here presented. 



Diameter in Millimeters 



No. 70 

 Sandy Silt 



No. 129 

 Silt 



No. 131 

 Clayey Silt 



No. 19 

 Silty Clay 



I-1/2 



1/2-1/4 



1/4-1/8 



1/8-1/16 



1/16-1/32 



1/32-1/64 



1/64-1/128. . . 

 1/128-1/256. . 

 1/256-1/512. . 

 1/S12-1/1024. 

 1/1024-1/204J 



•9 



11.9 



9.8 



28.7 



40.6 



5-9 



1-5 



tr. 

 tr. 

 tr. 



3-1 

 12.4 



37-2 



24.6 



9.6 



3-5 



■9 



tr. 

 tr. 



2-3 



2.0 

 5-6 

 13.2 

 26.4 

 19.8 

 17.8 

 10. o 



2-3 



composition, the number in Udden's table, and the name according 

 to the present classification. 



It will be pointed out that in order to name a sediment, one 

 must first make a mechanical analysis. This is true to the degree 



