30 Geological Reports on the State of New^ York. 



matter, or in other words, the operation of these forces furnishes us with 

 one mode of explaining how mineral veins have been filled." 



It is obvious, that the report of Prof. Emraons includes many 

 valuable facts and sound conclusions, which cannot be fully ap- 

 preciated, without an attentive perusal of the entire document. 



Third District — Counties of Montgomery, Herkimer, Oneida, 

 and Oswego. — By Lardner Vanuxem. 



This tract stretches from Lake Ontario easterly almost to the 

 Hudson, nearly crossing the State. It is particularly important, 

 from the uplift which a part of its strata have undergone, to form 

 the valley of the Mohawk. 



" The series of rock which forms the third district, from the Pennsyl- 

 vania line to the primary elevated region which separates the waters of the 

 Hudson from those of the St. Lawrence, inclines at a small angle to the 

 southwest, giving rise to that all important practical consequence and fact, 

 that every change of rock going north from the Pennsylvania line to the 

 limits mentioned, brings us to a lower and an older rock ; and on the 

 contrary, every new or different rock we arrive at going south, carries us 

 higher in the series, or nearer to the newest, the coal of Pennsylvania, 

 the final member of the great consecutive series of rocks o%our portion 

 of the North American continent. 



" The different groups, or series, or formations, of the third district, 

 have not all extended continuously over the limits mentioned, but ap- 

 pear, like the coal of the State mentioned, to have been restricted in 

 their progress north within certain limits, by a well defined east and 

 west line. 



" From the coal series to the Mohawk valley, the restriction or limit 

 has been confined, so far as observations have been made, to a single 

 series or group ; but at the Mohawk valley, throughout Herkimer and 

 Oneida, no less than five series terminate more or less abruptly, accord- 

 ing to locality, giving rise to that great depression, the Mohawk valley, 

 or conversely, the high range or great elevation which in these two 

 counties, and to the south of Montgomery, rises for a thousand or more 

 feet above the river. 



"The valley of the Mohawk, therefore, forms in all that part which 

 traverses the three above named counties, an all important geological 

 line of division. A high and an abrupt elevation, caused by the appear- 

 ance of the northern edges of the rocks of which it is formed, charac- 

 terizes the southern side of the valley ; whilst the northern side, being in 

 general formed of the inclined planes of the surfaces of the rocks which 

 pass under and support those of the great escarpment, presents nothing 

 in common with its southern border. 



