144 NEW YORK STATE MUSEUM 



large thickness of continental deposits. There is no vestige of 

 such deposits in the lower Mohawk trough, and no direct evidence 

 that they were ever deposited there. That a small thickness of such 

 material may have been laid down in the trough at this date is 

 by no means unlikely. The lower Mohawk trough, throughout its 

 history, has* had a tendency to sag, as contrasted with the territory 

 east and west of it. It would not be forced or unnatural to 

 assume that it participated somewhat in the sagging tendency which 

 was so prominently manifest in some neighboring troughs to the 

 east and south at this time. But if such deposits were formed 

 here they were in such slight thickness that every vestige of them 

 has since been removed by erosion. 



When were the great faults of the eastern Adirondack region 

 formed? And was the faulting wholly done during one single 

 period of disturbance, or has repeated dislocation occurred along 

 them since they were first formed? 



The repeated sags of the western trough would tend to form 

 fault breaks along its margins, separating it from the adjacent dis- 

 tricts, the Adirondack region on the west for example, whose 

 tendency has been to rise rather than to sag. It is therefore quite 

 possible that faulting began in the district early in the Paleozoic. 

 With every notable succeeding oscillation of level of the region 

 it is highly probable that renewed faulting would take place along 

 the breaks already in existence. Such an oscillation as that which 

 brought the Paleozoic to a close would be sure to be accompanied 

 by renewed movement along the fault planes. 



The early Mesozoic rocks of the easterly Appalachian troughs 

 have been greatly faulted since they were laid down. Obviously 

 this faulting must be of later date than the deposition of the rocks. 

 Most probably also this faulting was not confined to the mere 

 troughs of deposit, but affected the adjacent territory also. It 

 seems in the highest degree likely that further faulting occurred 

 in the Champlain region at this time. The faults of the eastern 

 Adirondack region are normal with nearly vertical fault planes, 

 and these certain Mesozoic faults are of similar type. 



On the other hand, the great overthrusts which have carried the 

 rocks of the eastern basin west to their present position, covering 

 much of the Schuylerville quadrangle, are faults of an entirely 

 different type. The question arises as to the relative age of the 

 two types of faulting. If the thrust faulting occurred before the 

 normal faulting it would seem that the thrust-faulted territory 



