368 New York State Museum 



New York formations. Devonian history in the area 

 covered by the present state of New York is compara- 

 tively simple. Devonian rocks are more widespread here 

 than rocks of any other age, covering nearly one-third 

 the area of the State (figure 50), and they have a com- 

 bined thickness of between 8000 and 9000 feet. The 

 mass of sediments represented by the Catskill mountains 

 is the most impressive single mass of Devonian rock in 

 the country. The Devonian strata along the Hudson 

 valley, as indicated by the outlier on the east side of the 

 river, formerly extended some distance to the east into 

 Massachusetts and perhaps the Connecticut valley. These 

 beds standing out now as a bold escarpment facing the 

 Mohawk valley must also have extended northward 

 across this valley to the southern Adirondacks. The 

 Silurian period passed into the Devonian with no dis- 

 turbance. The great limestone deposits of the New York 

 Devonian occur in the Lower and earlier Middle De- 

 vonian, the great bulk of the Devonian rock lying above 

 the limestones and consisting of huge deposits of sand- 

 stones and shales. Except for the nonmarine deposits 

 of the east, the Devonian rocks throughout abound in 

 fossils of marine organisms. The Upper Devonian beds 

 have furnished a wonderful flora of land plants includ- 

 ing tree ferns (Archaeopteris), seed ferns (Eosperma- 

 topteris) and giant club mosses (Protolepidodendron) . 

 The discovery of the "Gilboa" tree (seed fern) in the 

 Catskills has made that area famous and the "Naples" 

 tree (club moss) has done the same for western New 

 York. 



The classification of the New York formations fol- 

 lows ; dashes represent the absence of beds in the various 

 sections. 



