io : 2 Classes of Rocks. 



heim ; also in Hillsdale, Columbia county, N. Y. This man- 

 ganese is connected with an argillaceous iron ore, resembling 

 bog iron ore. 



III. Secondary Rocks. 



13. Millstone Grit. 



From Little Falls to lake Ontario, between Little and Big 

 Salmon rivers, this rock bassetts and is in fair view. Both 

 divisions occur near each other, and often in the same layer, 

 — the under side being always the sandy and the upper the 

 conglomerate. Coal mines in Europe are in connexion with 

 this rock, but have not as yet been found in this connexion 

 in our country. 



1 4. Saliferous Rock. 



Its bassetting edges lie directly on the millstone grit. Both 

 divisions, and all the varieties, but the conglomerate, may 

 be seen at Genesee Falls and in the banks of the Niagara 

 river ; also at Oak Orchard Creek. The conglomerate and 

 sandy varieties are seen on Connecticut river, and at New 

 Haven under the basalt ; also on the Hudson above New 

 York under the pallisadoes. Salt springs are found in it 

 every where west of Rome ; but none have been discovered 

 under the basalt of this country. 



15. Ferriferous Rock. 



It reposes on the saliferous rock every where west of Lit- 

 tle Falls. The sandy division lies over the slate, and a layer 

 of red argillaceous iron ore, about a foot or a foot and a half 

 in thickness, lies between them ; or alternates with the lay- 

 ers of one or both. The slaty division is generally green or 

 blue, and very soft. The sandy division is harsh, coarse, 

 and often conglomerate at the top. The softest variety of 

 the iron ore is called reddle, and is used as a paint. 



16. Lias. 



This general stratum does not agree in all respects with 

 European specimens which have been received in this coun- 

 try ; besides, no oolite has ever been discovered in connexion 

 with it. But it has so many characters m common with the 

 lias, that I venture to extend this name to it. Subdivisions. 

 Califerous slate forms the south ridge along the Erie canal 

 from Oneida to near Rochester ; also the lower part of Lock- 



