2o8 • NEW YORK STATE MUSEUM 



tory condition. This zone for a hundred feet is Hkely to be wet, 

 weak, and would require extra precautions and additional expense 

 in construction. 



6 Evidence of faulting. AMiichever interpretation of hole no. 

 40 is taken is in support of some displacement in the nature of 

 faulting between holes no. 40 and no. 45. If the gneiss rock floor 

 is not reached in hole no. 40, then the greater northward slope of 

 it from hole no. 45 to no. 40 than is shown from no. 46 to no. 45 

 indicates a downward movement. If on the other hand, the iden- 

 tity of the formation in the lower part of hole no. 40 be considered 

 undetermined, and its condition attributed to decay in a crush zone, 

 the presence of the crush zone itself indicates. movement of a fault 

 nature. 



Conclusions as to character of the crossing 



In considering the geological conditions as a factor in the prob- 

 lem of practicability of a tunnel, it is necessary to note the follow- 

 ing points : 



1 In view of the fact that the deepest point in the ancient chan- 

 nel is not yet found, and that it will probably go below -100 feet, 

 it would be necessary to figure on a tunnel grade down well toward 

 -300 feet. 



2 It would be necessar}^ to figure on a wet and weak zone of at 

 least 100 feet along the tunnel and a more expensive construction 

 at that point. 



3 The ground at such depth south of station 642 is unusually 

 sound. The ground north of station 6^6 may be counted good. 

 The ground between 636 and 640 may be considered fair, and the 

 ground from 640 to 642 -, troublesome, containing the chief ele- 

 ments of uncertainty. 



Fig. 36, which is a geologic section along the line at this point, 

 shows the distribution of these features drawn to scale. 



