MARINE SANDSTONE OF THE PARIS BASIN. 



231 



pressions to describe the pleasure experienced, in perceiving that, as 

 I discovered one character, all the consequences, more or less fore- 

 seen, of this character, were successively developed. The feet were 

 conformable to what the teeth had announced, and the teeth to the 

 feet ; the bones of the legs and the thighs, and every thing that ought 

 to reunite these two extreme parts, were conformable to each other. 

 In one word, each of the species sprung up from one of its elements. 

 Those who will have the patience to follow me in these memoirs, 

 may form some idea of the sensations which I experienced, in thus 

 restoring by degrees these ancient monuments of mighty revolutions. 

 This volume will afford much interest to naturalists, independent of 

 geology, showing them, by multiplied examples, the strictness of the 

 laws of co-existence, which elevate zoology to the rank of the ra- 

 tional sciences, and which, leading us to abandon the vain and arbi- 

 trary combinations that had been decorated with the name of systems, 

 will conduct us at last to the only study worthy of our age — to that 

 of the natural and necessary relations, which connect together the 

 different parts of all organized bodies. But geology will lose nothing 

 by this accessary application of the facts contained in this volume : 

 and thus the numerous families of unknown beings, buried in the 

 most frequented part of Europe, offer a vast field for meditation." 



Upper Marine Sand Qnd Sandstone. — In the Paris basin this for^ 

 mation covers the gypsum, or where that is wanting, it rests on the 

 calcaire grossier. The marine sand and sandstone is divided into 

 two beds ; the lower is without shells in situ, though some broken 

 fragments occur in it. This sandstone is frequently composed of 

 grains of transparent pure silex. and contains occasionally small 

 scales of mica. In some situations, this sandstone is penetrated by 

 calcareous infiltrations. In other situations, there are balls and masses 

 of much harder sandstone, which are used for paving stones in Pa- 

 ris, but they are not durable. At the forest of Fontainebleau in 

 France, the thickness of this sand and sandstone, exceeds one hun- 

 dred and seventy feet ; the sandstone occurs in loose blocks and ir- 

 regular masses, and sometimes is distinctly stratified. In some parts, 

 the sand is so pure that it is used in making the finest glass. In 

 other parts, the quantity of calcareous earth is so large, that it as- 

 sumes the form of calcareous crystals. There is no stratum of 

 this marine sandstone in England, but detached blocks of similar 

 stone, called (grey weathers) are scattered over some of the south- 

 ern counties, and some of the large stones at Stonehenge are of the 

 same kind. South of Nemours, in passing from Lyons to Paris, I 

 observed at considerable elevations, masses of this sandstone loosely 

 imbedded in sand, and as the sand\becomes washed away, these 

 masses fall out, and are scattered over the lower ground ; in this 

 manner, the occurrence of the blocks of grey weathers may be ac- 

 counted for : they are the remains of a formation of upper sand- 

 stone, which has disappeared in England. 



