90 On the Geographical Extent of [Feb. 



tional reason for attributing the same origin to the buhr-stones 

 (rneulihes) without shells ; for we know that, on the one hand, 

 these buhr-stones have much resemblance to certain flints 

 (silex) of the siliceous lime-stone; and on the other, that they so 

 much resembled the fresh-water buhr-stones with shells, that the 

 authors of the Mineralogical Geography of the Environs of Paris 

 had a difficulty to find decided characters to distinguish them. 

 It seems to me that analogies so strong, and uncontradicted by 

 any positive facts, are sufficient to establish this opinion. 



We may, to a certain extent, reason in the same manner on 

 the green marls of the neighbourhood of Damerie, which do not 

 contain shells, and are placed between two sets of beds of fresh- 

 water origin. I should here observe, that I have never met to 

 the east of Chateau-Thierry with traces of marine beds later than 

 the first fresh-water formation, as if the land in those parts had 

 been too much elevated to be covered by the waters of the sea, 

 which returned (perhaps repeatedly) to inundate the plain of 

 Paris. This fact is important, and merits an attempt to verify 

 it in a greater number of places. 



The country of which I have just given an account is one of 

 the best examples of the relations which exist between the geo- 

 logical disposition of the soil and its agricultural productions. 

 The whole of the chalky plain is cultivated, and produces corn. 

 The sides of the hills of lime-stone containing cerithia are cover- 

 ed with vines ; and as this lime-stone is almost always friable, 

 and has consequently spread itself over the chalky base of the 

 hills, the culture of the vine extends also to the level of the plain. 

 The real chalky soil is not in general fit for the growth of the 

 vine ; and it is well, in order to avoid an error that may arise 

 from the habit one has, in speaking of Champagne, of associat- 

 ing the ideas of a chalky soil with one that produces good wines, 

 to remark, that the vineyards producing what is called the 

 Champagne wine are generally on the exterior limits of this 

 district (region physique). Those of the western side, which 

 produce the most esteemed wines, are, as we have just seen, on 

 the beds of lime-stone with cerithia, and those of the eastern 

 side are on beds below the chalk, properly so called ; beds on 

 which I shall say a few words at the end of this memoir. Any 

 vineyards that occur in the interior of Champagne generally are 

 situated on some portions of one or other of these strata, which 

 are found isolated in the true chalk. 



The fresh-water lime-stone, and the marls which accompany 

 it, are not of sufficient thickness for the adoption of any pecu- 

 liar system of cultivation : often, indeed, the solidity of the 

 calcareous beds has caused them to form escarpments too verti- 

 cal to be cultivated ; but M. Desmarest, jun. has observed, that 



lime-stone is a part of the first of the first or lower fresh-water formation, but wr- 

 cannot admit the resemblance of the upper buhr-stones, whether they contain shells 

 or not, to the flints (silex) of the siliceous lime-stone. — French Editor. 



