CHAPTEE VI. 



Configuration of the Ground at Santo Domingo Excavation of Val- 

 leys Geology of the District Decomposition of the Rocks 

 Gold mining Auriferous Quartz Veins Mode of occurrence of 

 the Gold Lodes richer next the surface than at lower depths- 

 Excavation and reduction of the Ore Extraction of the Gold 

 "Mantos" Origin of Mineral Veins Their connection with 

 intrusions of Plutonic Rocks. 



THERE is scarcely any level land around Santo 

 Domingo, but in every direction a succession of hills and 

 valleys. The hills are not isolated ; they run in irregular 

 ranges, having mostly an east and- west direction, but 

 with many modifications in their trend. From the 

 main valleys numerous auxiliary ones cut deeply into the 

 ranges, and bifurcate again and again, like the branches 

 of a tree, forming channels for carrying off the great 

 quantity of water that falls in these rainy forests. The 

 branching valleys, all leading into main ones, and these 

 into the rivers, have been excavated by sub-aerial agency, 

 and almost entirely by the action of running water. It 

 is the system that best effects the drainage of the 

 country, and has been caused by that drainage. 



The wearing out of valleys near Santo Domingo pro- 

 ceeds more rapidly than in regions where less rain falls, 

 and where the rocks are not so soft and decomposed. 

 Even during the few years I was in Nicaragua there 

 were some modifications of the surface effected ; I saw 



