CattsJcill Group of New York, S?-t 



had not been recognised in my district, or adjacent to its southerns 

 limits. 



I consider that at this time there can be no doubt that the 

 Chemung group is identical with No. 9 in the original nomencla- 

 ture of the Pennsylvania Survey ; and the term Chemung group 

 having been adopted, and well understood in its relations and sig- 

 nification, and well marked by its fossils, we cannot with any 

 propriety continue to extend the term Cattskill group over a 

 large area occupied by the older rocks, and well characterised by 

 their contained fossils. 



Mr. Mather, in his descriptions of the rocks, has recognized the 

 Chemung group as lying below the Cattskill group, but, as I have 

 shown, the area colored by him as Chemung, is really Hamilton 

 group ; and it now becomes necessary to restrict the term Catts- 

 kill group to the beds above, or to those formerly known as X 

 and XI of the Pennsylvania Survey. 



Adopting this view, which is imperatively required of us, some 

 modification is necessary in the reference of certain fossils ; but I 

 am satisfied that it will remove one great cause of misunderstand- 

 ing relative to the groups of strata on the confines of the coal 

 measures ; and we shall avoid the complication which must ensue 

 from referring the same species of fossils to two distinct groups of 

 strata, according to the present application of our nomenclature. 



On reference to the Geological Reports of New York, you will 

 observe that the fossils of the Cattskill group, given in the 1st and 

 4th Districts, are of plants, with two species of shells. The red 

 shaly sandstone, (called old red sandstone or Catskill group,) rest- 

 ing in outliers on some of the higher hills in the 4th district 

 and occuring in continuous strata in Pennsylvania near the south- 

 ern limit of New York, did not afi*ord specimens of these plants 

 or shells ; while the scales and other remains of Holoptychius are 

 the characteristic fossils of the rocks in these western localities. 

 But so far as I am aware, no scales of Holoptychius have been 

 found in the area colored as Cattskill group in Delaware and the 

 adjacent counties on its west. 



In tracing the Chemung group westward, there are many indi- 

 cations that it may yet require to be restricted in its desio-nation 

 The Waverly sandstone group of the Ohio Reports, at one timi 

 regarded as entirely equivalent to the Portage and Chemuni 

 groups, may in its upper members constitute a distinct group 

 though we do not yet know any line of demarcation betweei 

 them. 



