336 J. J. Stevenson — Use of the JSame " CaUkilV 



lower portion ; each succeeding section in that direction shows 

 the fossiliferous portion extending higher and higher, until in 

 Huntingdon County, the whole mass below the Montrose sand- 

 stone, 4,675 feet thick, is more or less fossiliferous — the fossils 

 being most abundant in beds near the top of the column. In 

 southern Virginia, however, the change is more noteworthy, 

 for there within Roanoke County, the writer in 1890 found 

 Chemung forms far up in what is unquestionably the Catskill. 

 Going westwardly, one finds the matter equally clear, the fos- 

 siliferous beds occurring higher and higher, while the whole 

 mass diminishes in thickness ; so that before western Pennsyl- 

 vania has been reached Chemung fossils are present at the top 

 of the section, the Montrose or Catskill having thinned out 

 and disappeared. 



So then, the "Catskill condition" existed within a very cir- 

 cumscribed area until the close of the Chemung epoch ; but 

 for some reason, the area was enlarged greatly during the Cats- 

 kill. Red beds, it is true, had made their appearance at many 

 localities long before that time, but, for the most part, they 

 are insignificant features in the sections. It is sufficiently 

 clear that to apply the name Catskill to the whole series of 

 rocks would be to apply a term which would be misleading, as 

 it refers to a locality exhibiting characteristics wholly or almost 

 wholly absent from most or all of the section in nine-tenths of 

 the area in which the series can be studied within the Appa- 

 lachian region. 



Of course, there are objections to the use of the term 

 "Chemung" for the whole series; not much of the Catskill 

 portion is present in the immediate region where the Chemung 

 was studied by Hall in 1839. But undoubtedly there is a rem- 

 nant of that group there, so that representatives of all three 

 divisions of the series can be gathered under the name. The 

 only objections to the use of the name are such as apply to the 

 use of any geographical term ; but the reasons favoring its 

 use far outweigh any objections which may be offered. 



In probably nine-tenths of the area in which this series is 

 exposed within the Appalachian basin, the Chemung, that por- 

 tion below the Montrose or Catskill of Yanuxem, is the 

 important portion of the series ; it is the persistent portion, 

 with certain beds which are traceable directly over almost the 

 whole region outside of the Catskill Mountain area ; whereas 

 the Catskill is not the persistent portion, occupying as it does 

 only the long trough rudely parallel to the Blue Ridge from 

 southern New York to very near the Tennessee line, as already 

 defined. More than that ; the fauna, termed Chemung by 

 Hall in New York is typical of the whole section below the 

 Montrose sandstone and in Virginia passes even into that por- 



