158. Thus, a great degradation of the primitive mountains, and of course a great travelling of their materials, is proved to make a necessary part of the Neptunian theory. The extent of this travelling or transportation may be rendered more evident, if we apply a similar mode of reasoning to larger portions of the globe. The north-west of Europe furnishes us an instance of a very extensive tract of secondary country, comprehending the greater part of Britain, the whole of Flanders and Holland, part of Germany, the northern provinces of France, and probably the bed of the German Ocean, at least for a great extent. Within this circle almost all is secondary, and on the sides of it all round are placed ridges or groups of primitive mountains, namely the mountains of Auvergne, at least in part, and going round by the east, the Alps, the Vosges, the Hartz, the Highlands and Western Islands of Scotland, the hilly countries of Cumberland, Wales, and Cornwall. This zone of primitive mountains, on the supposition of the Neptunists, must have risen up in the form of islands in the great ocean, that originally covered the earth, forming a kind of circular Archipelago, including in its bosom a sea, which was from seven to five hundred miles in diameter. Over the whole of this extent, the _detritus_ of the above mountains must have been carried, in order to form the flat interjacent countries which are now exposed to our view. Such then, even on their own supposition, is the extent to which the Neptunists must admit that the materials of the primeval mountains were transported by the ocean. 159. This transportation of materials, may not be so great as that which is involved in Dr Hutton's theory, but is such as should make the enemies of his system consider, how nearly the principles they _must_ introduce, agree with those that they _would_ reject. This is one fact, out of many, which shows, that there is at present a much nearer agreement between the systems of geology, than between their authors.