SIGNIFICANT FEATURES OF DIAGRAMS 929 



be recast to the single-ratio basis, and plotted in integral diagrams, and 

 if these diagrams be criticall}^ examined for diagnostic features, several 

 such features may be picked out, some of which have already been dis- 

 cussed in print. First may be mentioned the comparatively high degree 

 of sorting shown by beach, and wind deposits, including both dune sand 

 and dust. Second, as might have been expected, glacial till diagrams are 

 low and broad, showing little sorting. Yet, surprising at it may seem, 

 few of them show no sorting at all. The few analyses of breccia available 

 show less sorting than the average glacial till, and yet, if the breccia has 

 shifted a little it may show signs of the peculiar obscure sorting of 

 talus. Whether the sorting of till is that of an unsorted mixture of many 

 kinds of residuum, or is of a different nature, has not been determined. 

 Some water deposits, particularly marine offshore deposits, show two 

 maxima, one of which is due to sorting and the other to the shells of some 

 very abundant organism. Third, Udden's inference that in eolian sands 

 the portion next in amount to the maximum is coarser in grain, and that 

 this is somewhat characteristic of eolian deposits, seems to hold in a gen- 

 eral way. However, although in diagrams of dune sands the column next 

 to the tallest is likely to be on the left or coarse side, in dusts, particularly 

 loess, it seems more likely to be on the right. Fourth, Udden's "Index 

 of sorting for aqueous sediments produced by drifting and silting'^ is 2% 

 to 1, and for "eolian sediments produced by analogous modes of blowing 

 and dusting" is near 4% to 1. This means that, on the whole, eolian 

 sediments of the kinds mentioned are much better assorted than aqueous, 

 and the ratios correspond to the ratios in heights between any column in 

 the integral diagram based on the ratio 2 and one next to it. 



Possibility of other significant Features being Found 



Perhaps other features, such as ratios of column heights, or of propor- 

 tionate amounts finer and coarser than the maximum, or some more ob- 

 scure but persistent character, may be brought out by further study, for 

 the diagrams of individual analyses are extremely variable. A part of 

 this variation is really not inherent in the sediment, largely because no 

 two analysts would agree exactly as to the composition of a sediment, and 

 because some samples analyzed have been taken from single thin layers 

 and others from an inch or more of deposit which commonly involves 

 several layers or conditions of deposition. 



