88 NEW YORK STATE MUSEUM 



while the harder bed is scarcely affected. This is well illustrated 

 by the contact line between the Onondaga and lower Hamilton 

 (Marcellus) formations wherever it is crossed by streams, the 

 Onondaga being a very resistant limestone formation while the 

 shales above it are easily removed. 



Age and structural relations of the strata. All the rock form- 

 ations outcropping in the Schoharie region were deposited 

 during three of the eras of Paleozoic time namely; the Oham- 

 plainic, the Siluric or Ontaric and the Devonic. Only a portion 

 of the Champlainic and Ontaric eras is represented by the form- 

 ations of this region, while the lowest or Cambric (Taconic), 

 and the highest or Carbonic of the Paleozoic eras are not repre- 

 sented. The former lies far below the surface, and could only 

 be reached by boring, while the latter, if it ever existed in this 

 region, has long since been worn away entirely. From Avhat has 

 been said regarding the southwestward dip of the strata, it will 

 be seen that the lower beds, hidden in the Schoharie region, will 

 appear from beneath their covering of higher beds as we pass 

 northward. If, for example, we follow the Schoharie creek 

 nortlnvard to its junction with the Mohawk at Fort Hunter, we 

 find successivel}^ lower and lower strata appearing in its bed 

 and banks, till on the Mohawk we have reached the Trenton 

 limestone which at Schoharie is approximately 3500 feet below 

 the bottom of the valley. If we i>roceed still farther north, we 

 find that twenty miles north of the mouth of the Schoharie kill 

 the crystalline rocks of Precambric age appear, which form the 

 Adirondack mountains, and lie approximately 4000 feet below 

 the valley bottom at Schoharie. If, on the other hand, we go 

 southwestward we meet with successively higher and higher 

 strata, even though we do not rise much above the level of the 

 Schoharie hills. It is not till we near the Pennsylvania line, 

 however, that we meet with rocks belonging to the Carbonic 

 era, and not till Ave have fjassed the state line, do we reach the 

 coal-bearing strata. The significance of this fact will be dwelt 

 on more fully in the discussion of the search for coal in this 

 region. The relationship is shown in the following diagram 

 [fig. 1]. 



