v.y2 



CATSKILI. DIVISION. 

 View in Gilboa. 



§ 3. Portage, ithaca and chemung geoups in the schoharie and hudson-river 



districts. 



The development of (lie Hamilton sliales is excessive in the eastern part of New-York, 

 but there are only slight differences in the lithological characters. At Summit in Scho- 

 harie county, in a deep gorge near the village, the Chemung group occupies the upper 

 part and the higher slopes adjacent to it, and also the hills above the village. As yet, 

 however, the fossils of the Clicmung narrows are not common or numerous ; and it seems 

 to be established that the fossils of the Hamilton shales go up higher into the shales and 

 flags, and occur nearer to the base of the Catskill division or Old Red sandstone, than at 

 the west. The flags at the top of the Helderberg range, and the rocks occupying the 

 highest position in the southern towns in Albany and Schoharie counties, belong to the 

 Chemung group. 



The purposes of agriculture do not require an identification of the rocks under conside- 

 ration : they belong chemically and mineralogically to the same class. The structure, the 

 tendency to decomposition, and the soil which is formed by disintegration, docs not differ 

 essentially in Albany county from that of Allegany or Cattaraugus county. We do not 

 find the exact equivalents when they are tested by fossils : it is possible, however, that 

 this may be owing to exposure. Other fossiliferous strata than those, for example, which 



