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 Potomac. We hear of limestone on the Mississippi and Ohio, and in all the mountainous country between the eastern and western waters, not on the mountains themselves, but occupying the valleys 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 Kentucky, which bear no resemblance to any I have ever seen on the tide-waters. 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 matter, 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 thirty-one inches height, which is equal to one of rain water of thirty-five feet high. If the whole contents of the atmosphere, then, were water, instead of what they are, it would cover the globe but thirty-five feet deep; but as these waters, as they fell, would run into the seas, the superficial measure of which is to that of the dry parts of the globe, as two to one, the seas would be raised only fifty-two and a half feet above their present level, and of course would overflow the lands to that height only. In Virginia this would be a very small proportion even of the champaign country, the banks of our tide-waters being frequently, if not generally, of a greater height. Deluges beyond this extent, then, as for instance, to the North mountain or to Kentucky, seem out of the laws of nature. But within it they may have taken place to a greater or less degree, in proportion to the combination of natural causes which may be supposed to have produced them. History renders probably some instances of a partial deluge in the country lying round the Mediterranean sea. It has been often[3] supposed, and it is not unlikely, that that sea was once a lake. While such, let us admit an extraordinary collection of the waters of the atmosphere from the other parts of the globe to have been discharged over that and the countries whose waters run into it. Or without supposing it a lake, admit such an extraordinary collection of the waters of the atmosphere, and an influx from the Atlantic ocean, forced by long-continued western winds. The lake, or that sea, may thus have been so raised as to overflow the low lands adjacent to it, as those of Egypt and Armenia, which, according to a tradition of