ADIRONDACK MAGNETIC IRON ORES 21 



rocks. The principal thrust has been evidently from the southeast 

 or northwest. From the fact that the eastern section has undergone 

 the greatest disturbance from its influence, the direction would 

 appear to be from the southeast rather than from the opposite point. 



The iron ore deposits afford many interesting examples of flexure. 

 Originally they -were probably straight tabular bodies formed 

 previous to the dynamism that has affected the inclosing rocks. In 

 some districts they have been very little disturbed, either along the 

 strike or on the dip. In others as instanced by the deposits of 

 Essex county, they have been flexed, twisted and made to assume 

 the most intricate shapes, around which the walls have been closely 

 molded. 



The existence of faults can be demonstrated in many cases where 

 the conditions are favorable for their detection, that is in areas 

 made up of contrasted formations, and their presence is indicated 

 elsewhere by topographic considerations. The probable close 

 connection between the present surface conformation and faulting 

 has been brought out more specially by Professor Kemp in his work 

 in Essex county. 



The main series of faults has a northerly trend, varying from 

 nearly due north to northeast. It approximately parallels the 

 longer axes of the ridges and tends to produce steep faces on the 

 northwest and southeast sides. This faulting may have been 

 responsible to some extent for the markedly uniform trend of the 

 ridges and valleys. In some cases the latter appear to occupy a 

 depressed strip between two parallel faults of this character. 



A second series of faults, which has probably resulted from the 

 movements initiated by the main series, trends away at varia- 

 ble angles, so that the ridges are divided into irregular blocks. 

 Examples of such block faulting in which the displaced portions 

 are more or less tilted form a characteristic feature of the interior 

 Adirondacks. 



The eastern and southern margins of the region have been 

 extensively faulted. In Clinton county Cushing has found the 

 Paleozoic strata to be frequently displaced by meridional faults, of 

 which one in Chazy township along Tracy brook has a throw of at 

 least 2000 feet, and cuts out the entire Beekmantown formation. 

 Most of the faults in this section downthrow to the east. It would 

 appear that the New York shore of the lower part of Lake Cham- 

 plain is limited by a series of meridional breaks forming a basin 

 tilted to the west. North of the Mohawk valley there are a number 

 of displacements trending northeast across the dip of the Paleozoic 



