GEOLOGY OF THE NORTH CKEEK QUADRANGLE 49 



bare wall of syenite rising to a height of a thousand feet or more 

 on the south side of Crane mountain is a truly impressive sight 

 as viewed from the valley or ridge just to the south. As viewed 

 from the summit of Crane mountain, the sharp-crested granite 

 ridge forming the westward extension of Little mountain bears 

 a close resemblance to a typical hogback ridge. All these mountain 

 masses show decided, though much more gradual, downward slopes 

 toward the north, this being perfectly shown by Crane and Huckle- 

 berry mountains and not so well by the Little mountain ridge. 

 Thus the general areal distribution and structural relations of the 

 rocks, more especially the long, regular or straight contact lines 

 between the Grenville and igneous rocks ; the high, steep walls of 

 igneous rocks rising above the Grenville ; and the distinct down- 

 ward tilt of the mountain blocks northward and away from the 

 scarps make the presence of three faults here practically certain. 

 The picture of Crane mountain (plate 8) clearly shows the char- 

 acter of this earth block with its steep scarp on the south and long 

 northward slope. 



For reasons already stated, nothing like exact figures can be 

 given as to the amounts of displacement but, judging by the pres- 

 ent height of the scarps, the throw of Crane mountain fault ap- 

 pears to be more than a thousand feet, while the throw of the 

 Huckleberry and Little mountain ridge faults are no less than 

 500 to 800 feet. The very rapid dying out of these faults is rather 

 remarkable, but perhaps not more so than in the case of the 

 Batchellerville fault of the Broadalbin quadrangle recently de- 

 scribed by the writer. 



As shown on the geologic map, a minor fault extends across 

 the top of Crane mountain and parallel to the great fault just south. 

 Three high points. 2682, 2829, and 3254 feet respectively, are 

 arranged along the crest of the fault scarp with very steep south 

 fronts or cliffs. The scarp on the south side of the highest peak 

 (3254 feet) is a sheer precipice more than 200 feet high, which 

 forms what is locally called the " Nose '' of Crane mountain. It 

 is well shown in plate 8. At several places the line of fracture is 

 marked by distinct crushed or sheared zones where the rock is 

 biotitic and almost like a schist in appearance. 



The eastern face of Crane mountain rises abruptly along a 

 straight line to a height of more than a thousand feet, and certainly 

 bears every resemblance to a fault scarp. This topographic evidence, 



*N. Y. State Miis. Bui. 153. p. 45- 



