202 ANNAL.S NFJW YORK ACADEMY' OF SCIENCES 



clearly shown to be of later age and the Inwood limestone-Manliattan 

 schist series cannot be the equivalent of the Wappinger limestone-Hudson 

 River slate series, represented here, but must be of earlier age and hence 

 pre-Cambrian. 



There are, therefore, at present two contrasting views : first, that the 

 Inwood limestone and ^lanhattan schist series is of Cambro-Ordovician 

 age, as held by Merrill, Dana, j\Iather and others ; and second that it is of 

 pre-Cambrian age, as held by Dr. Berkey. The present ^\Titer has made a 

 rather detailed, study of the Manhattan schist and its associated rocks as 

 developed in the southeastern portion of the State of Xew York south of 

 Highlands and has compared it with the Hudson River slates, phyllites 

 and schists north of the Highlands to see what light such a study might 

 throw on the problem from a petrographic standpoint. Typical localities 

 were studied in detail and most of the areas of schist exposed were visited. 

 A detailed structural study, however, involving very careful geologic map- 

 ping of large portions of the aica underlain by these formations was not 

 attempted. 



Manhattan Schist 



areal distribution 



The Manhattan schist is exposed in a series of fairly broad, roughly 

 parallel belts having a general northeast-southwest trend in the region 

 south of the Highlands of the Hudson and east of the Hudson River (see 

 map, PI. XY). West of the Hudson River the Newark formation of 

 Jura-Triassic age has concealed tliem with the exception of a small area 

 in the vicinity of Tompkins Cove just south of the Highlands. The 

 belted nature of the outcro]is of this and the underlying formations, as 

 has already been explained, is due to the erosion of a series of anticlines 

 and synclines whose axes have a northeast-southwest trend. The schist 

 occurs as far north as the southern portion of Putnam Coimty in this 

 area. Farther north the rest of Putnam and the southern portion of 

 Dutchess County are underlain by the older gneisses of the Highlands, 

 the younger formations having been entirely removed by erosion. The 

 use of the term '^Manhattan" has been confined entirely to those schists 

 which make up the uppermost or youngest of the bedrock formations oc- 

 curring in southeastern ISTew York State in New York, Westchester and 

 Putnam Counties. Tn Connecticut the continuation of the schists has 

 been described under the name of "Berkshire," as given to them by the 

 Connecticut Geological Survey.^ ** 



"Conn. Geol. and Nat. Hist. Surv. BiiH, No. (», pp. 91-02. 1906. 



