Notes upon the Geology of the Western States. 55 



of the coal-field, the same rocks can be seen. Near the Cuya- 

 hoga falls, and along the river below, at Newbnrgh, and at sev- 

 eral other places, may be seen the equivalents of the Portage and 

 Gardeau rocks of the New York reports, but of greatly dimin- 

 ished thickness. The Portage sandstone, however, is in con- 

 siderable force in many places in Ohio, being known as the 

 " Waverly sandstones" of the geological reports. This term has 

 also been erroneously applied to a portion of the conglomerate of 

 the coal group when free from pebbles. The Chemung, Portage, 

 and Gardeau groups form the only rocks seen along Lake Erie 

 shore, from Dunkirk in New York to Cleveland, Ohio, and they 

 extend still farther west until the limestone from beneath rises 

 to the surface. These three groups in Ohio present no essential 

 differences, and may without impropriety be considered as one, 

 the lower part being mostly of shale, the middle of sandstone, 

 and the upper part of shales and flagstones. Fossils are not 

 abundant in the upper member, and no other than fucoides ap- 

 pear, except very rarely in the two below. In the Ohio reports, 

 all these rocks are usually spoken of as non-fossiliferous. 



The casts of mud furrows which in New York form the dis- 

 tinguishing character of the Gardeau mass, are in Ohio equally 

 continued through the Portage and Chemung groups, shewing 

 there at least, that some of the same causes were in operation 

 during the deposition of the three. These casts of mud furrows 

 present some interesting features in the rocks of New York, 

 which will be more fully explained at another time. 



These groups reappear on the western side of the axis in In- 

 diana, all together occupying less than three hundred feet in 

 thickness. It is here that we first discover evidences of a very 

 important change. The upper part of the mass, which I con- 

 ceive to be the same as the Chemung, is quite sandy, with a few 

 traces of fossils characteristic of that group in New York, with 

 here and there thin seams or wedgeform layers of limestone, 

 made up of crinoidal fragments and broken shells, portions of the 

 mass being often oolitic. These thin layers contain a species of 

 Productus, differing from any in the Chemung of New York. 

 Finally, we discover a mass of limestone eleven feet thick, inter- 

 stratified with the sandstone, the lower or smaller portion com- 

 posed mostly of fragments of organic remains, while the upper 

 portion is a perfect oolite. Other thinner masses are seen inter- 



