GEOLOGY. 227 



the various kinds of tliis limestone oliserved in (Iiv(ms parts 

 of Europe. There is an experiment which would, as we 

 conceive, place the matter beyond a doubt : this would be 

 an analysis of the limestone, with a view to ascertain the 

 quantity of magnesia w^hich it contains, and we regret nuich 

 that the loss of our specimens has deprived us of the oppor- 

 tunity of this analysis. But we think the case sufficiently 

 - strong to justify us in considering this as the formation cor- 

 responding to tlie magncsian limestone of England, and to 



the rauchwacke and zechstein of Thuringen. 



****** 



" The features which we observed from the Wasscmon to 

 the Wisconsin are extremely interesting. At a distance of a 

 few miles northwest of the former stream, the vegetation 

 presented a sudden and striking change, announcing a cor- 

 responding one in the geological character of the country. 

 We ascended a rough, steep, and hilly ground, which was 

 covered with heavy timber, and with a very thick underwood, 

 consisting principally of young oak and aspen. This thick 

 brushwood continued for about two miles, wdien w^e struck 

 the bank of a small stream remarkable for the beauty of its 

 scenery, which differed from any that we had hitherto met 

 with. The brook runs in a deep and narrow glen, the sides 

 of which are very steep, and, in some places, vertical. 

 They are covered, at their summit, with a dense vegetation, 

 which extends over the edge of the rock, and imparts a 

 cliaracter of austerity and of gloom to this secluded valley, 

 which hnds not its parallel in any that we recollect ever to 

 have seen.* The dark color which the water receives from 



• This stream is an upper branch of the Pcctanon, on its fight bank, 

 about 8' south of lat. 43°. It may not be easily comprehended by some of 

 our readers, how a valley exceeding all others in austerity and gloom could 

 be remarkable for the beauty uf its scenery. We are quoting only the 



