Naturalists, who have examined the various parts of the earth, almost all agree in this, that great effects have been produced by water moving upon the surface of the earth; but they often differ with respect to the cause of that motion, and also as to the time or manner in which the effect is brought about.  Some suppose great catastrophes to have occasioned sudden changes upon the surface, in having removed immense quantities of the solid body, and in having deposited parts of the removed mass at great distances from their original beds.  Others again, in acknowledging the natural operations which we see upon the surface of the earth, have only supposed certain occasions in which the consequence of those natural operations have been extremely violent, in order to explain to themselves appearances which they know not how to reconcile with the ordinary effects of those destructive causes.

The theory of the earth which I would here illustrate is founded upon the greatest catastrophes which can happen to the earth, that is, in being raised from the bottom of the sea, and elevated to the summits of a continent, and in being again sunk from its elevated station to be buried under that mass of water from whence it had originally come.  But the changes which we are now investigating have no farther relation to those great catastrophes, except in so far as these great operations of the globe have put the solid land in such a situation as to be affected by the atmospheric influences and operations of the surface.

The water from the atmosphere, collected upon the surface of the earth, forms channels to itself in running towards the sea or lower ground; and it is these channels, increasing in their size as they are diminished in number by the uniting of their waters, that give so clear a prospect of the operations of time past, and prove the theory of the land being in a continual state of decay, and necessarily wasted for the purpose of this world.  Every description, therefore, of a river and its valleys, from its sources in the mountains to its mouth where it delivers those waters to the sea, is interesting to the present theory, which is the generalization of those facts by which the end or intention of nature is to be observed.  M. Reboul, in a Memoir read to the Academy of Sciences at Paris in 1788, has given a very distinct view of the Vallee du Gave Bearnois dans les Pyrenees; there are many things interesting in this memoir; and I shall now endeavour to avail myself of it.

“Le torrent qui porte le nom de Gave de Pau parcourt depuis sa source pres des limites de l’Espagne, jusqu’a la petite ville de Lourde, une vallee qui se dirige du sud au nord sur une longueur d’environ dix lieues.  Cet espace, qui forme son lit dans l’interieur des Pyrenees, ressemble moins a une vallee dans la majeure partie de son etendue, qu’a une entaille etroite et profonde, dont les flancs sont souvent coupes a pic d’une hauteur effrayante,