6a 

 Historioal Geolorv . 

 l. u^-fQhg.gaAT -Crystalllne— fo^nid on vestern part of Long Island— 

 Astoria and Hell Gate and Long Island City. in Brooklyn such rocks 

 hawe heen struck by Artesian wells. Chiefly gneiss and granite. 

 These rocks have no influence on flora. 



2. The Paleozoic and early Meso5ioie unrepresented until v/e come to 

 the Tgrtig-rv and Cretaceous represented by the clays underneath the 

 drift. In the south the soil is entirely so. yellow sands and gravels 

 age unknown. Merrill's theory that these deposits represent an earlier 

 glacial epoch. Wlienev^r this gravel is in contact with drift, it 

 is always below it and always above known tertiary deposits. The 

 present cofastal plain of Long Island was once much more extended, 

 out to the hundred fathom line. Buried rivers in this vicinity, as 

 Hudson. At close of cretaceous period, probably Long Island was. 

 continuous with New York. New Jersey and Ilass. separated from Conn, 

 by a freah water stream. 



Soil probably glacial on north side and boundary absolutely 

 distinct between hills on north from plain on south. Hills average 

 250 ft. in height. Higliesr hill. Harbor Hill, near Roslyn, 391,ft. 

 A second moraine on north coast gives its shape to the coast. 

 Between these two moraines is a plain, well-marked. Terminal moraine 

 stops on a southern slope — this positive proof of glacial advance. 

 South slope probably was an overwash from the glacier. 



Glacial clay or till, best deposits in Brooklyn. Sands and 

 gravels in Kames, in other parts. Also boulders of gneiss and granites. 



