Geological and Miscellaneous Notice of Tarapaca. 



and can be traced for several hundred yards ; they are compact, 

 hard, and dry, and at a little distance resemble veins of quartz. 

 Barely a trace of insoluble matter was found in specimens taken 

 from different parts of several veins. Some of the cavities afford 

 small rhombic crystals. 



In the northern and eastern parts of the province are numerous 

 quebradas. or abrupt ravines, commencing at the base of the 

 Cordilleras and extending in a westerly direction ; some of them 

 intersect the pampa and both ranges of mountains, others termin- 

 ate at its eastern border, dividing the eastern range only. Nu- 

 merous similar ravines intersect the country situated between 

 the Andes and the sea, both north and south of the province 

 we are describing. A remarkable feature disclosed by them is a 

 difference of level on the sides, which has evidently been occa- 

 sioned by the upheaving of the one or the subsidence of the 

 other. 



These quebradas vary in depth from a few hundred feet to three 

 thousand feet below the level of the plain, and in width from a 

 hundred yards to five or six times that distance. The bottoms 

 are covered with sand and pebbles, bowlders of porphyry, feld- 



spar, and granite, and huge angular fragments of trachyte, sand- 



stone, and gypsum. In various parts of these ravines, where the 

 rock is exposed, both on the bottoms and on the sides, are deep 

 scratches or grooves, running in the direction of the ravine. 

 The sides present bold precipices. On those of the quebradas 

 which terminate at the border of the pampa, near the mountain 

 of Chalocolo, water lines are plainly discernible; and the crevices 

 in the rock, at an elevation of several hundred feet above the 

 plain, are filled with the same kind of clay which covers for 

 miles this p&rt of the pampa. 



The quebradas are generally barren ; but in some parts of that 

 of Pisagua, alfalfa is raised in considerable quantity. In the 

 eastern parts of these of Camarones, Chisa, Pisagua, and Tili- 

 viche, are small streams which take their rise in the Andes ; they 

 are absorbed or evaporated before they reach the sea. 



Beneath the surface of a part of the pampa, lies an extensive 

 forest of large trees, all of which are more or less inclined to the 

 southwest. They are, for the most part, of the Algarobo species. 

 The wood is dark brown, inclining to red, and very brittle ; it 

 burns freely and with little smoke, although it contains a large 



