GEOLOGY OP THE NORTHERN ADIRONDACK REGION 407 



In addition to these greater, meridional faults, differential 

 slipping in the fault strips has resulted in the production of a 

 multitude of cross faults, trending away from the greater ones 

 at all angles, downthrowing now to one side and now to the other, 

 and thus dividing the strips into a number, often a large number, 

 of blocks of varying size and shape, producing great confusion in 

 the stratigraphy and tending to disguise the larger features of 

 the region. These are mostly a feature of the Champlain region 

 and have not the persistence westward of the meridional breaks.^ 

 As a general rule, they have a somewhat east and west trend but 

 with wide variation in direction. They downthrow now to the 

 north and now to the south, with frequent production of small 

 sunken blocks, downthrown on both the bordering faults. They 

 are in general dip faults, shifting the rocks along the strike, while 

 the large strike faults are apt to cause disappearance of a con- 

 siderable '[^'.rt of the rock section of the district on the two sides 

 of the fault [fig. 3, 4] . Thus along the great Tracy brook fault, 

 in Chazy township, the entire Beekmantown formation is faulted 

 out, bringing the Chazy and Potsdam together on opposite sides 

 of the fault. A small portion of the course of this fault is shown 

 on the accompanying map [pi. 12]. Just within the map limits 

 its course is more nearly northeasterly than is usual with the 

 great faults and more nearly so than is the case with most of the 

 course of this special fault. About 1 mile to the southeast a 

 parallel fault is seen, and the strip which intervenes between the 

 two is intricately cut up by a number of cross faults, much more 

 so than is true of the district adjoining the strip on either side. 

 Along this pair of faults the entire Beekmantown formation, at 

 least 1500 and likely 1800 feet in thickness, is faulted out, together 

 with an unknown thickness of the Potsdam, from 100 feet to 300 

 feet at least, and a portion of the Chazy, so that the throw of 

 the fault is 2000 feet or more. It is not a true strike fault, since 

 the dips hereabout are swerving from an easterly, to a northeast- 

 erly or northerly direction, but they are so low that the general 

 effect of disappearance of a certain thickness of strata from the 



^Tlie Mohawk valley faults and some of the larger Champlain faults are 

 well shown on the large geologic maps of the State. The two large 

 scale maps of portions of Clinton county [pi. 13, 13] better illustrate the 

 general character of the faulting in the Champlain district. 



