MINEEAt 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 names of Sierra de Acha, Sierra de Los 
Mimbres, Sierra Yerde, and Sierra de las GruUas, 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 cliaius 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 Oaxima and Cosicpiiriachi (lat. 10|-° — 29°) ; the alluvial soil 
that contains dissseniiiiatcd gold, extends some degrees still 
further northwards. It is a very striking phenomenon, that 
the gold- washing of Cinaloa and Sonora, like that of Darba- 
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 Paste and Popayan to the gulf 
of Nieoya (lat. 1^°— 9.^°), become very frequent on the 
western coast of Giiatimala (lat. 9^°— 16°) ; these traces of 
fire again cease in tlie gneiss-granite mountains of Oaxaca, 
and re-appear, perhaps for the last time, towards the imrtli, 
in the central Cordillera ot Anahuac, between lat. 18^ and 
19A°, where the volcanoes of Taxtla, Orizaba, Popocatepetl, 
Toluca, Jorullo, and Colima, appear to he situated in a 
crevice* extending from E.S.E. to AV.N.W., from one 
ocean to the other. This line of summits, several oi u hicii 
enter the limit of perpetual snow, and which are the loitiest 
of the Cordilleras froin the peak ol Tolima (lat. 40 46 
north), is almost perpendicular to the great axis ol the chain 
of Guatimala and Auahuac, advancing to the 27th parallel, 
uniformly N. 42° E. A characteristic feature ot 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 ot the 
parallel of Puerto de Navidad, in lat. 19° US' j and, like the volcano of 
Tnxtla, if not beyond the zone, at least beyond the avarage paraffel of the 
volcanic fire of Mexico, which parallel seems to be between 18 a9 , and 
19° 12'. 
VOL. in ^ 
