S22 1\€W Ohervatmis on Volcanoes and their Lava, 



?ti\s volcano has been rounded, and has assumed a regular 

 fonii, by the overflowing of all those matters which have 

 not been pushed out with sufficient force, or which were too 

 light to roll to a distance. If wc were to count the diffe- 

 lent eruptions of the Cotopaxi by the multitude of different 

 layers of burnt stones which are at the foot of it, without 

 even having regard to the inferior layers which are broken 

 and overturned, the last burning would be at least the 

 twentieth ; and it would appear that each eruption sent out 

 substances of different colours and of various descriptions, 

 and that they have been successively shot out accordingly 

 as they are differently arranged in the bosom of the moun- 

 tain." 



With the slender knowledge of lithology and geology 

 which the times afforded, M. Bouguer turned his attention 

 to the substances of these m -"uutains which attracted his no- 

 tice ; and according to what he has said on the subject, and 

 from the manner in which he expresses himself, we easily 

 perceive that every thing is of a volcanic nature, from the 

 base to the summit of these mountains. This black sand, 

 attracted by the magnet, resembles the ferruginous sand on 

 the shores of Naples ; and these deep ravines, the sections 

 of which show the work of the fire, are similar to the rugged 

 fe.ce of Mount Somma hanging over the narrow valley which 

 separates it from the Vesuvius of the present day, where 

 everv thing also is the work of fire. 



Bouguer had an opportunity of seeing closely the ravines 

 he mentions : he traversed a great number of them in ascend- 

 ing frofJtCaracol, situated at the foot of the Cordelier, to the 

 valley of Quito. The ascents and descents were so frequent, 

 that it occupied him seven days in travelling a distance of 

 only eight or nine leagues in a right line. He at last arrived 

 at the foot of that pai t of ChimboraQO which hangs over the 

 valley. These numerous ravines, which furrow the declivity 

 of the Cordelier from its base, hollowed out by the torrents 

 produced by the abundant rains which fall in this country, 

 show that the substances of which these declivities are formed 

 are quite distinct from each other, like all the heaps of vol- 

 canic matters. 



Tjic 



