Maryland Geological Survey 145 



strength would represent a minor admixture to a larger quantity of its 

 average size. In this way would result the difference between marine and 

 wind sediments shown by diagrams C and J, p. 170, in that in the marine 

 deposits, which are essentially the products of wave action, the next largest 

 quantity after the maximum is in the next finest material, while in dune 

 sands, which are essentially current-deposits, it is in the next coarsest. 

 That is to say, in wave-worked material there would be an admixture of 

 finer material which had escaped the maximum wave strength, while in 

 current-deposits the products of their greatest strength would appear as 

 the admixture and the finer material produced by their average strength 

 would survive as the maximum. 



That some sorting action and not the advent of coarser material is 

 responsible for the presence of a smaller amount of very fine sand in bed 3 

 (sample 6, F, p. 169) than in bed 2 (sample 5, E, p. 169) appears from 

 the fact that there is actually more of coarse, medium, and fine sand 

 together in the argillaceous sample 6 than in the sandy sample 5. It may 

 still be, in view of our imperfect knowledge of the mechanical composi- 

 tion of sediments, that in spite of the divergence of sample 5 from typical 

 wave-worked sediments it is nevertheless the product of deposition in 

 more open water, perhaps as a result of the deepening suggested above, 

 and that as deposition continued, or possibly uplift of the region replaced 

 subsidence, the area in which this section was deposited became cut off as 

 a lagoon or estuary. But the interpretation that the difference is due to a 

 local current which passed over the area when the lower bed (bed 2) was 

 being deposited, but disappeared before the deposition of the upper bed 

 (bed 3), seems the more probable. 



The position of the line of limonite staining between beds 2 and 3 

 is probably determined by distance from the surface and porosity com- 

 bined. Such lines are common throughout the region and by their wavy 

 form and lack of relation to the lithology show that they are secondary 

 and formed by circulating ground waters. 



Bed 4 may represent shallowing of the water, but as it is at the top of 

 the section its sandy yellow appearance is more probably due to alteration, 

 so that in the absence of an analysis nothing definite can be said about it. 



