68 J. R. Reeves — The Anderson Esker. 



sizes must have been deposited by a swift current for it 

 would require suck a current to move rocks of this size. 

 There being no fine sand in these layers lends evidence 

 to the supposition that the current was swift. Likewise 

 the strata of fine sand was evidently deposited by a 

 gentle current, supporting evidence to this being the 

 absence of large rocks. 



An interesting feature found in one exposure was a 

 sand-filled pocket. A study of this showed that the 

 upstream end of the pocket was composed of the largest 

 grains, the sand of the pocket becoming finer toward 

 the downstream end where the smallest grains were 

 found. Evidently, as the current with its load flowed 

 into the pocket, the velocity was checked, thus causing 

 some of the largest particles of the load to drop, and as 

 the flow continued to be checked more of the load was 

 dropped, the sizes varying according to the ability of 

 the current to carry them. 



A collection of rocks taken from the southern end of 

 the esker ranging in size from one-fourth inch to one 

 and one-half inches in diameter was sorted, measured, 

 and the kind of rock determined. Below is a table 

 showing the results. 



Shape. Composition. 



Round 11% Limestone 75% 



Sub-angular 25% Granite 24% 



Angular 64% Vein quartz .... 1% 



It was found that the larger sizes contained a higher 

 per cent of round rocks than the smaller sizes. The 

 table shows the largest part of the material carried by 

 the stream to be limestone, also that the majority of the 

 rocks were angular showing that they were' not carried 

 far else they would be more rounded. 



Indiana University, Bloomington, Ind. 



