MINEBAL VEINS. 321 



the most elevated, runs first from south-east to north-west, 

 by Zacatecas towards Durango, and afterwards from south 

 to north, by Chihuahua, towards New Mexico. It takes 

 successively the nnmes of Sierra de Acha, Sierra de Los 

 Mimbres, Sierra Verde, and Sierra de las Grullas, and about 

 the 29 and 30 of latitude, it is connected by spurs with 

 two lateral chains, those of the Texas and La Sonora, which 

 renders the separation of the chains more imperfect than the 

 trifurcations of the Andes in South America. 



That part of the Cordilleras of Mexico which is richest in 

 silver beds and veins, is comprehended between the parallels 

 of Oaxaca and Cosiquiriachi (lat. 1G 29) ; the alluvial soil 

 that contains disseminated gold, extends some degrees still 

 further northwards. It is a very striking phenomenon, that 

 the gold-washing of Cinaloa and Sonora, like that of Barba- 

 coas and Choco, on the south and north of the isthmus of 

 Panama, is uniformly situated on the west of the central 

 chain, on the descent opposite the Pacific. The traces of a 

 still-burning volcanic fire which was no longer seen, on a 

 length of 200 leagues, from Pasto and Popayan to the gulf 

 of Nieoya (lat. 1^ 9^), become very frequent on the 

 western coast of Guatiinala (lat. 9-J- 16) ; these traces of 

 fire again cease in the gneiss-granite mountains of Oaxaca, 

 and re-appear, perhaps for the last time, towards the north, 

 in the central Cordillera of Anahuac, between lat. 18 and 

 19|, where the volcanoes of Taxtla, Orizaba, Popocatepetl, 

 Toluca, Jorullo, and Colima, appear to be situated in a 

 crevice* extending from E.S.E. to W.N.W., from one 

 ocean to the other. This line of summits, several of which 

 enter the limit of perpetual snow, and which are the loftiest 

 of the Cordilleras from the peak of Tolima (lat. 40 46' 

 north), is almost perpendicular to the great axis of the chain 

 of Guatimala and Anahuac, advancing to the 27th parallel, 

 uniformly .N. 42 E. A characteristic feature of every 



* On this zone of volcanoes is the parallel of the greatest heights of 

 New Spain. If the survey of Captain Basil Hall afford results alike 

 certain in latitude and in longitude, the volcano of Colima is north of the 

 parallel of Puerto de Navidad, in lat. 19 36' ; and, like the volcano of 

 Tuxtla, if not beyond the zone, at least beyond the avarage parallel of the 

 volcanic fira of Mexico, which parallel seems to be between 18 59', and 

 19 12'. 



VOL. in * 



