248 J. F. Kenvp — Extension of the Cortlandt Series. 



proximately !N". 40. E. It covers about three-quarters of a 

 square mile and is surrounded on all sides by the gneissic rocks 

 of what Dr. Britton has called the Iron-bearing Group. At 

 the southwest it encloses a bed of limestone now changed to a 

 compact crystalline marble, which shows, as will be noticed 

 further on, peculiar evidences of contact metamorphism. 

 Around the edge of the eruptive area the gneiss is fissured by 

 small dikes, and itself bears witness of having been subjected 

 to some powerful action. It breaks in small angular lumps, 

 loses its bedding or lamination, and under the microscope ex- 



hibits the large normal crystals of orthoclase broken into innu- 

 merable smaller masses which polarize as individuals. Between 

 the Stony Point area of the original Cortlandt Series and the 

 nearest outcrop of the Kosetown area about one mile intervenes. 

 This is made up of a narrow band of much contorted schist in 

 the immediate vicinity of Stony Point, of the Tompkins Cove 

 blue limestone and the Archaean gneiss. On the south, the 

 Triassic conglomerate and shales'* form the surface but in no 

 place do they come in contact with the eruptives and their dip 

 and strike are widely different from the limestone. In C, 9 and 



* Russell. I. H., Annals N. Y. Acad. Sci., vol. i, (1878), p. 237. 



