REPORT OF THE DIRECTOR AND STATE GEOLOGIST 



i-Tl 



intrusion being the cause of the foliation, nor does the latter 

 show parallelism to the edge of the main intrusive masses of the 

 Adirondack^. It can be equally well, perhaps better 3 explained 

 as due to a force acting from the southeast, or from the north- 

 west, presumably the former, and acting at several different 

 times. On the latter assumption the decreasing perfection of the 

 foliation in the successively younger rocks would be explained. 



Nothing that could be definitely recognized as bedding has been 

 observed in the Dannemora gneiss. Granite injections parallel 

 to the foliation planes often give a bedding effect, as do also cer- 

 tain bands of hornblende gneiss, which cut across the foliation 

 and are held to represent ancient, diabase dikes. With these ex- 

 ceptions the different varieties of gneiss fade into one another 

 instead of being sharply marked off. 



Faults. The region of which the Mooers sheet is a part is an 

 excessively faulted one, not only great breaks but many minor 

 ones occurring. Their detection is a matter of great difficulty 

 over much of the territory, owing to widespread drift covering 

 and specially to the uniformity in lithologic character of the 

 pre-Cambrian rocks and of the Potsdam sandstone. 



The greatest break known in the vicinity is that which has 

 been called the Tracy brook fault. 1 This is easily traced, run- 

 ning in a northeasterly direction, across the whole of Chazy town- 

 ship with the Potsdam sandstone on one side and the various 

 members of the Chazy limestone on the other, the entire Cal- 

 ciferous being faulted out. Its course is easily traced from the 

 point where it enters the sheet, north of West Chazy, to the point 

 where the brook leaves the fault line. Beyond, its course is con- 

 jectural. If produced, it would touch the northeast extremity of 

 Rand hill, along whose eastern edge there is unquestionably a 

 fault of great magnitude, the cliff being a fault scarp whose 

 present relief is due to the more resistant character of the rock 

 on the west, possibly aided by recent movement. The way in 

 which the Potsdam contact on the north climbs the hill, rising 

 from 800 feet to 1400 feet within a distance of 3 miles, is strongly 



1 loth an. rep't X. Y. state geologist. 1S95. p. 570. 



