PLEISTOCENE GEOLOGY OF NASSAU CO. AND BOROUGH OF QUEENS 651 



Concerning the origin of tlie Jamaica bay depression, it is inti- 

 mately associated with another feature, the Far Rockaway ridge 

 ah'eady mentioned as extending northeastward on the southeast side 

 of the bay till it disappears beneath the sands of the frontal plain 

 near Lynbrook. The structure of this ridge is not well revealed. 

 So far as the superficial deposits go, they appear ev^erywliere to be 

 yellowish quartz gravels up to 3 inclies in diameter. Like the 

 depressed area northwest of it, the ridge appears certainly to be 

 older than the surface features of the plain in its vicinity. 



Barn urn's island, lying to the east of the Far Rockaway ridge, was 

 not visited ; but the following well section, reported by Dv F. J. H. 

 Merrill several years ago, would seem to indicate that the Far 

 Rockaway gravel extends in that direction. The normal sediments 

 of the out wash plain would be, at least at surface, at this distance 

 from the moraine fine sand rather than gravel. 



WELL SECTION ON BARMUM's ISLAND^ Feet 



Sand and gravel, stratified 70 



Clay and clayey sand with lignite 56 



Gravel and fine sand with clayey sand , . 44 



Blue clay, clayey sand and silt, with lignite and pyrites 168 



Crosby agrees in referring the upper 70 feet to the yellow gravel. 



The elevation of the ridge is quite uniformly a little more tlian 

 20 feet above the sealevel ; its direction is parallel with the moraine 

 on the north of it. This association of a depression which appears 

 to have been in the process of filling by streams pouring from the 

 ice front, with a bar of gravels older than the outwash plain, as their 

 composition and form show, suggests the deformation of the 

 Columbia or some underlying coastal plain formation at some time 

 anterior to the completion of the moraine and its frontal plain. 

 Such deformation might well arise as the effect of the imposition of 

 the weight of the ice sheet on the yielding sediments previously 

 deposited. In this view, the Far Rockaway ridge is an outlying, 

 upraised fold, or " parma," ^ and the bay a correlated depressed area, 



^ Merrill, F. J. H. Geology of Long Island. N. Y. acad. sci. Annals. 1886. 

 3 : 350. 

 2 Suess, Edouard. La face de la terre. Paris. 1897. 1 : 830. 



