TABLE OF CONTENTS XXvii 
Page. 
Great coal formation on the borders of New-York, and others of North America.296 
Gluantity of coal..... 297 
Disturbances of strata since the carboniferous era. 297 
CHAPTER VI. 
NEW-YORK SYSTEM. 298 
Rocks embraced in this system. 298 
Name, why given.298 
General remarks. 298 
Rocks upturned, overturned, etc. in Hudson valley.. 298 
Difficulties of identification. 298 
Cause of the formation of this system. 298 
Area covered by these rocks. 298 
Thinning out of some of the western strata. 299 
Maximum development of, most in Catskill mountains. 299 
Explanation of rarity and abundance of fossils.299 
Division of the subject: Catskill division; Erie division; Helderberg division; Onta- 
division; Champlain division. 299 
1. Catskill division.299 
Composition... 299 
Fossils and figures. :. 300 
Four general divisions: Conglomerates and grits; red shales and grits; grey and green¬ 
ish grits and slates; chocolate grits and shales. 302 
Geographical extent in New-York. .. 302 
Joints. 302 
Section of the Catskill mountains. 303 
At Post’s mills... 305 
Descriptions of the vicinity of these sections •. 306 
Terraces and topographical features. 306 
Conglomerate limestone. 306 
Localities where sections can be seen, and descriptive geology. 306 
Plants (fossil). 306 
Oblique lamination of the strata. 306 
Rock-houses. 311 
Disintegrated strata and enormous blocks. 312 
Coal if found, where. 313 
Topographical and agricultural characters. 313 
Ripplemarks.. 313 
Useful minerals. 314 
2 . Erie division. 317 
Synonims. 317 
[Geol. 1st Dist.J 7* 
