S115AERIAL OUTWASII 287 



tioned. Eastward the shore is very cleai at Farmingdale ; also on the 

 moraine hills north of Eastport and East Qnogne, and specially clear 

 northwest of Bridoehanipton. 



The lack of distinct sliorelines between the submerged and the exposed 

 portions of the sand-plain is doubtless the reason why later geologists 

 found no genetic distinction betAveen the higher and lower 1)elts of the 

 plain, but regarded the whole plain as snl)aerial out wash. But this lack 

 of distinct beaches on tiie surface of the sand-plain is not a valid argu- 

 ment against submergence. On the contrary, it is the natural condition 

 Avhen all the various factors are considered. The land was rising and the 

 zone of wave-work was steadily falling. The waters lapping on the gently 

 sloping sand-plain were subject to considerable variation of level. In 

 addition to the tidal fluctuation, there is to be added the lifting or de- 

 pressing of the water le^el l)y severe storms. This vertical range ma}' 

 well have been 10 to 15 oi- possibly 20 feet, which would give a horizontal 

 range of the water on tlie low gradient plain of at least one or two miles. 

 Bars are usually weak or absent on plains of sand or fine gravel, the 

 reason for which is given later (page 300). 



It should be noted that both Salisbury and AYoodworth have written 

 that the Long Island plain did not exhibit the normal features of sub- 

 aerial outwash. The drainage is too well distributed; the channels are 

 not on the apexes or crests of the swells or "isms/' but between the broad, 

 flat areas. The lobations are too broad and flat for glacial stream deltas, 

 and the channels are too indefinite and fail in continuity. There is a 

 remarkable lack of coarse materials on the swells and even along the 

 creases or so-called channels. 



Any one inclined to insist on the subaerial origin of ' all the plain 

 should answer these questions : Can any plain with similar topography 

 be found anywhere along the whole extent of the terminal moraine, unless 

 where clearly faced by standing water? Is it really possible for alluvial 

 fans, built of the coarse materials swept out of the ice-front, to unite and 

 blend together so as to produce such continuous, smootli plains? Is it 

 likely that streams draining the ice-sheet were ever so e\enly spaced and 

 so equal in volume as to produce such level plains? 



Tlie stronger or more definite channels are above the theoretic marine 

 level. A good example is seen northeast of Farmingdale, along the east 

 side of the AVest Hills; between the moraines, west of Dix Mills ; one lead- 

 ing from Commack to Edge wood, and ib rough the later moraine from 

 Brooklyn to Koslyn, as noted by Wood worth. Some allowance must be 

 made for storm wasli and stream-work since the land uplift; but this is 

 more noticeable along the outer border oT the plain, which lay in deeper 



