22 NEW YORK STATE MUSEUM 



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extends under cover of glacial drift where such deposits effectually 

 conceal the underlying rocks, this being particularly true east and 

 southeast of Franklin Falls, west and north of Wilmington, and 

 north of Clifford Falls. So far as known at present, this White- 

 face type of anorthosite appears to be relatively more abundant in 

 the Lake Placid quadrangle than in any other portion of the Adi- 

 rondacks. Professor Kemp has described similar rocks as occur- 

 ring in smaller amount in the Elizabethtown quadrangle. 



The Whiteface anorthosite is most irregularly distributed with] 

 reference to the other rocks. One reason for this is that the later 

 syenite-granite intruded it so very irregularly. Although the 

 Whiteface anorthosite is quite certainly a differentiation phase of j 

 the Marcy anorthosite, and, in a broad sense, may be regarded asj 

 a border f acies of that rock, nevertheless it does not form well- 

 defined borders about the Alarcy anorthosite as the gabbroic facie* 

 do about the anorthosite of the Long Lake and Elizabeth to wn| 

 quadrangles mapped by Professors Gushing and Kemp respectively. 

 The largest area of Marcy anorthosite is, to a considerable extent 

 at least, flanked on either side by Whiteface anorthosite. On the 

 north, however, the Whiteface rock is more extensively developed 

 than the Marcy rock. Also, some small mappable bodies of both 

 Whiteface and Marcy anorthosite are isolated from the larger 

 bodies. It is by no means uncommon to find within the areas of 

 Marcy anorthosite small local developments of rocks which greatly 

 resemble the Whiteface type and vice versa. In short, the differen- 

 tiation of the anorthosite magma was asymmetric and this, com- 

 bined with the very irregular intrusion of the later syenite-granite 

 body, accounts for the very uneven distribution of the anorthosite. 



By far the largest area occupies much of Wilmington, White- 

 face and Esther mountains, Knapp hill and vicinity, and the 

 vicinity of Franklin Falls. An area several miles long mostly occu- 

 pies the valley of the West Branch Ausable river from The Flume 

 to near Connery pond. Several square miles of the Whiteface 

 anorthosite occur in the vicinity of Keene, and a little over i square 

 mile in the vicinity of Upper Jay. Areas of less than i square 

 mile are located as follows: the southern base of Catamount 

 mountain; i mile north of Middle Kilns; 1^4 miles northeast of 

 Wilmington ; southern slope of Little Whiteface mountain ; on 

 H'awk island, and on a portion of Moose island in Lake Placid; 

 along the river west of Malcom pond ; 2^ miles northeast of Keene;, 

 one-half of a mile south of Keene; and i}^ miles southwest ofj 

 Upper Jay. 



