Handbook of Paleontology 209 



Within this area are many of the highest points of the 

 Adirondacks, Mich as Mount Marcy and VVhiteface moun- 

 tain. The syenites occur principally as a number of 

 local intrusions found abundantly in the Adirondacks 

 outside of the anorthosite area, and arc especially well 

 developed in Franklin county. The granites are the 

 most abundant of the intrusives, though occupying 

 relatively small areas and are closely associated with 

 the « rrenville series. Some characteristic exposures are 

 those in the Thousand Islands which are known to 

 l>c younger than the syenites. The age of some of 

 the other intrusions is in doubt, and there may have 

 been several different periods of intrusions. The gab- 

 by os are best developed in Essex and southern Frank- 

 lin counties. Some gabbros grade into the anortho- 

 sites but others are definitely known to be younger 

 than the anorthositcs, syenites and granites. The dike 

 rocks are the youngest of the Precamhrian intrusives 

 and the diabase dikes are the most abundant. They 

 were intruded in late Precambrian time and are very 

 numerous in Clinton and Essex counties, but less 

 abundant on the western side and elsewhere. 



The Precambrian sedimentary rocks of southeast- 

 ern New Y<»rk are found in the Highlands of-the-Hud- 

 son on the wesl side of the river and extend in a 

 southwesterly direction through Orange and Rockland 

 counties into Xew Jersey. < >n the east side of the 

 river they extend north from Xew York through 



Westchester, Putnam and Dutchess counties, passing 

 into Connecticut The name Fordham gneiss has been 



given to a complex series of conformable and inter- 



bedded gneisses, schists, quartzites and limesti 

 considered equivalent in age to the Grenville series 



