ſeparately were little different from that: by which it appears, that theſe lamina are, in the main parallel with the axis of the earth. In ſome Inſtances, indeed, I found them perpendicular, and even reclining the other way: but theſe were extremely rare, and always attended with ſigns of convulſion, or other circumſtances of ſingularity, which admitted a poſſibility of removal from their original poſition. Theſe trials were made between Madiſon's cave and the Patowmac. We hear of lime-ſtone on the Miſſiſippi and Ohio, and in all the mountainous country between the eaſtern and weſtern waters, not on the mountains themſelves, but occupying the vallies between them.
Near the eaſtern foot of the North mountain are immense bodies of Schiſt, containing impreſſions of ſhells in a variety of forms. I have received petrified ſhells of very different kinds from the firſt ſources of the Kentucky, which bear no reſemblance to any I have ever ſeen on the tidewaters. It is ſaid that ſhells are found in the Andes, in South-America, fifteen thouſand feet above the level of the ocean. This is conſidered by many, both of the learned and unlearned, as a proof of an univerſal deluge. To the many conſiderations oppoſing this opinion, the following may be added. The atmoſphere, and all its contents, whether of water, air, or other matters, gravitate to the earth; that is to ſay, they have weight. Experience tells us, that the weight of all theſe together never exceeds that of a column of mercury of 31 inches height, which is equal to one of rainwater of 35 feet high. If the whole contents of the atmoſphere then were water, inſtead of what
