The _graywacke_, which in this very general and hasty view we have considered as in part belonging to the clay-slate of transition, appears to us to form the connecting link between that clay-slate and the old red sandstone. In attempting to give a more detailed account of these formations, we might perhaps speak of the graywacke as others have done, as a distinct stratum. We have, however, usually found it so intimately blended either with the sandstone or clay-slate, that in this enlarged view we see no necessity for a separation. We cannot agree in opinion with some who have considered the graywacke as the substratum of the great secondary formation of the valley of the Mississippi. We have found it almost invariably overlaid by an inclined sandstone, separating it from the secondary rocks towards the west. This may not be as often the case at the north, as in Pennsylvania, Maryland, and Virginia. Mr. Eaton is of opinion, that "graywacke underlays all that district of country in the interior of the state of New York, which would be bounded on the north by a line drawn from Albany westward to the Onondaga salt springs; on the west, by a line running from the salt springs by Bath to the Pennsylvania line; on the south, by a line running thence to Newbergh on the Hudson, above the highlands; and from thence to Albany, by a line running parallel to the river, at a few miles distance." We are informed by Governor Clinton,[95] that coal strata exist in the western part of the state of New York, and we are induced from the analogy of the other parts of the same great secondary formation, to believe that the brine springs of Onondaga rise not from graywacke, {328} but from the sandstone of that coal formation. According to Maclure,[96] old red sandstone appears from under the limestone and other strata at Lewestown, ten miles below the falls of Niagara, and also near the salines of Onondaga in Genessee county. "This," says he, "would give some probability to the conjecture that the old red sandstone is the foundation of all this horizontal formation, and is perhaps attached to some series of rocks laying on the primitive north of the Great Lakes."