GEOLOGY OF THE LAKE PLACID QUADRANGLE 37 



No. 24, from Keene gneiss area just north of Keene; no. 25, by the 

 road at southeastern base of Cobble hill; no. 27, quarry at southeastern 

 end of Lake Placid; no. 28, by the road one-half of a mile north-northeast 

 of Keene; no. 29, near the road one-half of a mile north of Keene; no. 

 30, by the road one-half of a mile west of Big Cherrypatch pond; no. 33, 

 by the road one-third of a mile west of Copperas pond; no. 36, White- 

 face brook, I mile froim the lake; no. 38, i^ miles north-northeast of 

 Keene; no. 39, from tongue of syenite cutting Whiteface anorthosite i 

 mile south of Morgan pond; no. 43, i mile west of High fall; no. 32, quarry 

 by the road five-sixths of a mile north of Malcom pond; no. 40, by the 

 river three-fourths of a mile west-southwest of Owen pond; no. 31, 

 granitic syenite from middle eastern shore of Buck island in Lake 

 Placid; no. 47, granite from the small area in Wilmington notch; no. 48, 

 granite from the gorge at High fall of Ausable river; no. 46, granite 

 porphyry from side of new road one-half of a ^mile southwest of Franklin 

 Falls; no. 49, granite porphyry from the gorge one-half of a mile south 

 of Keene. 



There is no evidence that the syenite cuts the granite of the 

 quadrangle, or vice versa, but a gradation from one into the other 

 seems to be clearly shown in many places as, for example, on 

 Catamount mountain ridge, on Wilmington mountain, and on the 

 southern slope of Mt Whiteface. In a few cases the change from 

 syenite to granite occurs within such short distances that the inter- 

 mediate granitic syenite can not be mapped. Proof that the syenite 

 is younger than the anorthosite has already been given. 



As usual in the Adirondacks, this syenite is definitely known to 

 be younger than the Grenville series. In certain localities the 

 syenite contains masses of Grenville rocks as inclusions, this being 

 particularly true near its borders with the Grenville. Such 

 inclusions are nearly always arranged with their long axes parallel 

 to the foliation of the syenite. Some of these inclusions are to 

 be measured in inches, others in yards or rods, and still others are 

 large enough to be separately indicated on the geologic map. Good 

 examples of small inclusions may be observed on Cobble hill (east 

 of Lake Placid village), and in Styles brook on the western border 

 of the Grenville area. Some of the areas of mixed gneisses show 

 Grenville rocks all cut to pieces by, and intimately associated with, 

 syenite as, for example, 2 miles north-northeast of Keene, and i 

 mile northeast of Keene. 



Basic phase of the syenite. But one mass of rock of this kind 

 has been separately represented on the accompanying geologic map. 

 It lies in the valley of West Branch Ausable river east of Connery 

 pond. The area is i% miles long, with a maximum width of nearly 



