The rising and sinking of the land in this way can only be directly and positively proved in places which lie along the sea shore, for nowhere else is there any exact standard of comparison by which the rising or falling may be measured. But it is now generally believed by geologists and philosophers that a state of gradual motion, rising in some places and sinking in others, is the natural and constant condition, or, as it is more scientifically expressed, the normal condition of the strata which form the crust of the globe. Of the causes which lead to this state of things it would be out of place to speak here, but there is no doubt of the fact; and this action is in no part of the world going on so actively and with so sensible an effect as on some of the coasts of America.

Now, although these changes of level proceed in an extremely gradual manner, so that the inhabitants that dwell upon the territory thus slowly rising or falling are, in most cases, wholly unconscious of the motion, still the effect might be sufficient, in the course of forty or fifty centuries, to submerge a very extensive tract of land, which in remote ages may have formed a connection between the American continent and other lands lying to the eastward or westward of it.

The Plants and Animals of America Generally New.

These and various other similar theories were devised in former times in endeavors to contrive some way of bringing plants and animals from other countries to America; but they have been generally considered unsatisfactory, since on coming fully to examine the plants and animals living here, they were found to be, as it seemed, essentially different from those found in other countries, so different as to render it very improbable, according to the ideas on this subject that have hitherto generally prevailed, that they could ever be descended from the same stock, at least by ordinary generation. The fauna and the flora were both found to be in general essentially dissimilar.