UPPER PALEOZOIC (dEVONIC). 231 
the " Chemung Period " by Dana, and divided into the Portage 
and Chemung stages. The deposits attain a thickness of two or 
three thousand feet in New York and Northern Pennsylvania, 
and farther south are represented by 5000 feet of sandy deposits, 
coarser toward the top, and with occasional gravel conglomerates, 
This series of deposits is characteristic of the eastern area, and is 
not recognized in the central or western areas. It is linked by 
its flora with the eastern border sections, and by its fauna is 
recognized as intimately associated with the upper Devonian 
deposits of North Devonshire in England. 
The faunas of the upper Devonian change rapidly in com- 
position on passing westward from the Appalachian ridges, and 
the pure Chemung type is scarcely recognized west of western 
New York and Pennsylvania, although some of its species are 
seen in the Iowa and Nevada sections. Passing into Ohio, 
Canada West and Michigan, the upper part of the Devonian 
assumes a distinct type, which is more closely allied with that of 
the Indiana and Illinois sections. It appears to be a prevalence 
of the conditions expressed in the Genesee shales and associated 
Portage shales and sandstones of New York, with the failure of 
the Chemung rocks and fauna, running up into shales and sand- 
stones of the Waverly and closing with conglomerates. The 
more eastern sections, after the Hamilton, run up into sandstones, 
red and gray shales, sandstones of considerable thickness, and 
conglomerates, and present no trace of any marine fauna inter- 
mediate between the Chemung and the Carboniferous. As we 
approach the Ohio border going westward the Chemung fauna 
also fails, and the Waverly follows the Hamilton with only the 
fauna of the black shales intervening. 
In the eastern part of New York, Pennsylvania and south- 
ward, the coarse sands and conglomerates with red and green 
shales, prevail after the Plamiltou stage, reaching a thickness of 
6000 or 7000 feet, and then the Chemung fauna is sparse and 
confined to the lower strata. This red shale and sandstone type 
is called the " Catskill group " in New York, the " Cadent 
series " of the Pennsylvania nomenclature. In the eastern Ap- 
palachian area this same lithological type of rocks continues all 
the way upward to the coal measures; green and red shales, sand- 
stones and conglomerates, and occasionally thin beds of limestone, 
but with no trace of the marine faunas which characterize the 
