346 Dr Boue on the Formation lyf Tertiary Rocks. 



higher than the ocean, or which, with a lower bottom, were se- 

 parated from the ocean by a chain aiFording only exit to a 

 small stream of water. Probably the elevations during the al- 

 luvial period hastened the change or conversion of the salt-wa- 

 ter basins into fresh-water lakes, or their drying up entirely. It 

 is also evident that in some countries the elevation of the coun- 

 try has been followed by a sudden retreat of all the sea-water, 

 and then streams were established ; or, in favourable circum- 

 stances, a bank has permitted the accumulation of water, and 

 one or more fresh-water lakes have been formed, as in Auvergne 

 If that district had not had, during the deposit of the Paris ma- 

 rine limestone, a different level from that of the neighbourhood 

 of Paris, marine limestone would also have been deposited there. 

 M. Brongniart will be convinced of it, as soon as he renounces 

 bis opinion that at Montmartre there is a fresh-water deposit, a 

 theory long ago rejected by Professor Jameson (in 1816), for 

 his theory admitted the finding of true fresh-water rocks in 

 Auvergne. M. Brongniart was naturally led to the conclusion 

 that both basins had the same level. We think that many 

 things tend to shew that Beaumont is right in placing the ter- 

 tiary limestone of Auvergne as parallel with that of Fontain- 

 bleau, and with the gypsum of Montmartre, a proposition which 

 is in concordance with the opinion which maintains that there 

 existed a difference of levels. Such, then, are the considerations 

 suggested to us by M. Brongniart's opinions. We may be wrong 

 in many things, but we are right in some. Our observations 

 are not to be viewed as depreciating the incontestible merit of 

 M. Brongniart, who has formed at Paris a particular school of 

 geology, and has in this way given a new direction to geologi- 

 cal science. 



On the Consumption of Gold and Silver in Britain in the 

 Twenty Years between 1810 and 1829, hut especially on 

 the application of them, to other purposes than Coin. By 

 William Jacob, Esq. F. R. S. 



X HE greater part of the application, both of gold and silver, to 

 other purposes than the fabrication of money takes place in 



