He then reiterates the view that these deposits of marble and limestones, often forming mountain ranges, could not have been the result of a universal catastrophe, and in a very modern way goes on to specify what the limits of catastrophism are. The only catastrophes which a naturalist can reasonably admit as having taken place are partial or local ones, those dependent on causes acting in isolated places, such as the disturbances which are caused by volcanic eruptions, by earthquakes, by local inundations, by violent storms, etc. These catastrophes are with reason admissible, because we observe their analogues, and because we know that they often happen. He then gives examples of localities along the coast of France, as at Manche, where there are ranges of high hills made up of limestones containing Gryphææ, ammonites, and other deep-water shells. In the conclusion of the chapter, after stating that the ocean has repeatedly covered the greater part of the earth, he then claims that "the displacement of the sea, producing a constantly variable inequality in the mass of the terrestrial radii, has necessarily caused the earth's centre of gravity to vary, as also its two poles.[79] Moreover, since it appears that this variation, very irregular as it is, not being subjected to any limits, it is very probable that each point of the surface of the planet we inhabit is really in the case of successively finding itself subjected to different climates." He then exclaims in eloquent, profound, and impassioned language: "How curious it is to see that such suppositions receive their confirmation from the consideration of the state of the earth's surface and of its external crust, from that of the nature of certain fossils found in abundance in the northern regions of the earth, and whose analogues now live in warm climates; finally, in that of the ancient astronomical observations of the Egyptians. "Oh, how great is the antiquity of the terrestrial globe, and how small are the ideas of those who attribute to the existence of this globe a duration of six thousand and some hundred years since its origin down to our time! "The physico-naturalist and the geologist in this respect see things very differently; for if they have given the matter the slightest consideration--the one, the nature of fossils spread in such great numbers in all the exposed parts of the globe, both in elevated situations and at considerable depths in the earth; the other, the number and disposition of the beds, as also the nature and order of the materials which compose the external crust of this globe studied throughout a great part of its thickness and in the mountain masses--have they not had opportunities to convince themselves that the antiquity of this same globe is so great that it is absolutely beyond the power of man to appreciate it in an adequate way!