286 H. L. FAIRCHILD POST-GLACIAL SUBMERGENCE OF LONG ISLAND 



All the existing or positive features of both plains are jnst those which 

 should be expected in a giacial ontwash laid down nnder the sea. The 

 important characters, specially the equivocal ones, will be considered in 

 the later chapters. 



SUBAERIAL OUTWASH 



The diversit}'- of view and the failure of some students of Long- Island 

 geology to recognize the evidences of submergence may be partly due to 

 their theories of elevation, but is also explained by the dual character of 

 the plain. The later geologists, making more detailed study of the com- 

 plex morainal tracts, approached the plain from the viewpoint of the 

 moraines, and naturally emphasized the out wash origin of the plain, 

 which is the true genesis of some portions of the higher plain, where it 

 laps on the moraines. The absence of any clear line of demarkation be- 

 tween the subaerial and the subaqueous belts encouraged t]ie view of sub- 

 aerial outwash for the entire breadth of the plain. 



The writer concedes that some portions of the plain were built by the 

 glacial outwash above the reach of the sea. On the map (plate 10) an 

 attempt is made to indicate these areas, which show more clearly on a 

 large map of the assembled topographic sheets. 



The areas of the plain which appear to have been built seaward, so as 

 to fill the shallow waters and exclude the sea, lie north of a line connect- 

 ing the villages of Queens, Hempstead, Deer Park, Brentwood, and Eon- 

 konkoma. From Farmingdale eastward the railroad lies on the marine 

 plain. The most extensive single area of subaerial outAvash is the district 

 of New Hyde Park, Mineola, Hempstead, and Hicksville (Oyster Bay 

 and Hempstead quadrangles). Smaller areas lie between the detached 

 moraine masses, as follows: A strip between tlie Bethpage Hills and Hall' 

 Hollow Hills, or northeast of Farmingdale; north of Deer Park and 

 Brentwood; between the southern and the northern moraines, the district 

 of Green lawn, Larkfield, and Commack (JSTorthport quadrangle), and a 

 belt facing the northern moraine between Smithtown and Eocky Point 

 (chiefly on the Setauket quadrangle). 



East of Yaphank, along the earlier (southern) moraine, and east of 

 AVading Elver, along the later moraine, there are no subaerial outwash 

 plains. All the plains in the eastern half of the island were wave-leveled, 

 and only the higher parts of the moraines stood above the sea. 



The stronger lobations of the outwash have some relation to the breaks 

 in the moraines or the channels which were the exit of heavy drainage, 

 as noted by Woodworth. 



The line of contact between moraine and wave-smoothed gravel plain 

 is a good ghoreline >yest of Jamaica that has long been noted and ques- 



