398 Tertiary Formations, paet ix. 



point between S. and SSE. with an inclination in 

 the central lines of abont forty degrees, and in the 

 outer ones of under twenty degrees. This band of 

 symmetrically troubled country is about eight miles in 

 width. 



The island of Qairiquina, in the Bay of Concepcion, 

 is formed of various soft and often ferruginous sand- 

 stones, with bands of pebbles, and with the lower strata 

 sometimes passing into a conglomerate resting on the 

 underlying metamorphic schists. These beds include 

 subordinate layers of greenish impure clay, soft mica- 

 ceous and calcareous sandstones, and reddish friable 

 earthy matter with white specks like decomposed crystals 

 of feldspar ; they include, also, hard concretions, frag- 

 ments of shells, lignite, and silicified wood. In the 

 upper part they pass into white, soft sediments and 

 brecciolas, very like those described at Chiloe ; as in- 

 deed is the whole formation. At Lirguen and other 

 places on the eastern side of the bay, there are good 

 sections of the lower sandstones, which are generally 

 ferruginous, but which vary in character, and even pass 

 into an argillaceous nature ; they contain hard concre- 

 tions, fragments of lignite, silicified wood, and pebbles 

 (of the same rocks with the pebbles in the sandstones 

 of Quinquina), and they alternate with numerous, often 

 very thin layers of imperfect coal, generally of little 

 specific gravity. The main bed here is three feet thick ; 

 and only the coal of this one bed has a glossy fracture. 

 Another irregular, curvilinear bed of brown, compact 

 lignite, is remarkable for being included in a mass of 

 coarse gravel. These imperfect coals, when placed in a 

 heap, ignite spontaneously. The cliffs on this side of 

 the bay, as well as on the island of Quiriquina, are 

 capped with red friable earth, which, as stated in the 

 ninth chapter, is of recent formation. The stratifica- 



