INTRODUCTION. Sitt 



So far therefore from there having been land in the place of that part 

 of the present Atlantic which lies to the south of Labrador, as has been 

 usually supposed, this region was then equally an ocean and of great 

 depth. For not only do we find these calcareous beds of the Hudson-river 

 group many hundreds of feet in thickness, but also the limestones below, 

 some of them holding in greater profusion the same and similar species 

 of fossils which mark their occurrence on the west of the Green mountain 

 range. The direction of the coarser accumulations, therefore, would indi- 

 cate the source of these to have been on the east and southeast. 



From whatever source, however, we are to look for the sediments of this 

 period, it is clear that the existence of a large part of the western slope 

 of this mountain barrier, the Appalachian chain, in Canada, Vermont, 

 Western Massachusetts and Eastern New- York, is due to the original ac- 

 cumulation of materials during this period, rather than to any subsequent 

 influence which has broken up and dislocated the successive beds of the 

 formations composing it. In proof of this we have only to look at the 

 enormous thickness of the sediments in their normal condition ; and we 

 shall be forced to admit that however much broken and plicated and 

 degraded by subsequent denudation, the great mass or quantity of these 

 materials must still remain a strong feature in the line of their accumula- 

 tion. 



Since, however, the sedimentary strata of this period, along their line 

 of greatest accumulation, are complicated with those of later periods, we 

 must postpone the full discussion of the principles involved in the question 

 of sedimentary accumulation, and consequent disturbance, folding, and 

 metamorphism of strata, and the production of mountain chains, till we 

 have considered facts relative to the source and direction of the sediments 

 during later epochs. 



In the State of New- York, the period of the termination of the Hudson- 

 river group is well marked by the non-fossiliferous arenaceous formations 

 known as the Oneida or Shawangunk conglomerate and gray sandstone 

 of Oswego : these appear to be identical with the Cillery sandstones and 



