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of volcanoes is traversed. the highest being the Cerro de San Juan; their 

 form is rounded on top, but witli steep slopes, and the lava is a dai'k ba- 

 ste material f uU of green spherules, wbich are not much elongated in any 

 direction; this lava appears to have been exuded in a pasty condition, for 

 it shows no sigas of beddiug or flow. The river has cut a narrow winding 

 gorge through it, -with steep but not vertical sides Above San Juan de 

 Dios, at San Ignacio, is the junction of the Batopilas river, in a more open 

 cotmtry; also showing some signs of alluvial deposits. 



The Batopilas river flows between steep cliffs of basalt and diorite, 

 apparently lower members of the great platean series, and not recent erup- 

 tions like those of San Juan and Eealito. Near Puebla, granite with nu- 

 merous dykes and patches of schorl is exposed; and generally the great 

 variety and numerous sections of the rocks in this district would make 

 it interesting te a geololist, who had time to study them. On occount of its 

 ruggedness it is useless, except for mining, and is accordingly a retreat 

 for the wild Tarahumara; whose dark red forms may be seen bathing in 

 the river, and at night the light of fires in the caves they inhabit, gleams 

 in the lofty recesses of the hills. 



Batopilas is a considerable mining town, its mineral veins have been 

 worked since the early years of the Spanish occupation, and they are now 

 exploited by a United States company, wich, alone out of many mining 

 concerus in these provinces, uses modern methods and machinery. The 

 principal veins are of crystallized native silver imbedded in calcite, the 

 country rock being a hard diorite. One mine extends 900 feet above, and 

 the same depth below the adit; and the author saw a blast fired in a vein 

 one foot wide coutainig 75 per cent, of bright metallic silver. Other neigh- 

 bouring mines contain silver as sulphide. The mountains round Batopi- 

 las have been stripped of their wood for f uel at the mines, and when seen 

 from above appear covered with a ramifying network of small ravines, by 

 which the whole surf ace is made steep, the slopes from two arroyos always 

 terminating in a sharp ridge; this extreme effect of denudation may be 

 due to removal of the natural covering. 



Leaving Batopillas we reach the Cerro Colorado, an immense red mass 

 of low gi-ade, auriferous rock; it was recently worked on a considerable 

 Bcale at a losa, and the machinery is still on the spot; costly transport waa 

 the chief obstacle to success. We now cross over the cordón to the Url- 

 que valley, and go up to the town; although the rock walls are 5000 feét 

 high, and very preeipitous, the valley has a narrow flat floor composed of 

 alluvial material» deposited under water (during the existance of the vol- 

 canic dam). Nearly every kind of tropical fruit does well here. It is poa- 

 sible to go far up the valley near the river, a path having been blasted 



