chap. xin. Cleavage of Clay-Slate. 449 



latter localities the cleavage has been much obscured 

 by the metamorphosed and feldspathic condition of the 

 slate. Within the area of these several islands, in- 

 cluding Navarin Island, the direction of the stratifica- 

 tion and of the mountain-chains is very obscure ; though 

 the mountains in several places appeared to range in 

 the same WNW. line with the cleavage : the outline 

 of the coast, however, does not correspond with this 

 line. Near the bifurcation of the Beagle Channel, 

 where the underlying metamorphic schists are first seen, 

 they are foliated (with some irregularities) in this same 

 WNW. line, and parallel, as before stated, to the main 

 mountain-axis of this part of the country. Westward 

 of this main range the metamorphic schists are foliated, 

 though less plainly, in the same direction, which is 

 likewise common to the zone of old erupted trappean 

 rocks forming the outermost islets. Hence the area, 

 over which the cleavage of the slate and the foliation of 

 the metamorphic schists extends with an average WNW. 

 and ESE. strike, is about forty miles in a north and 

 south Hue, and ninety miles in an east and west line. 



Further northward, near Port Famine, the stratifi- 

 cation of the clay-slate and of the associated rocks is 

 well defined, and there alone the cleavage and strata- 

 planes are parallel. A little north of this port there is 

 an anticlinal axis ranging NW. (or a little more westerly) 

 and SE. : south of the port, as far as Admiralty Sound 

 and Gabriel Channel, the outline of the land clearly 

 indicates the existence of several lines of elevation in 

 this same NW. direction, which, I may add, is so uni- 

 form in the western half of the St. of Magellan, that, 

 as Captain King l has remarked, i a parallel ruler placed 

 on the map upon the projecting points of the south 

 shore, and extended across the strait, will also touch 

 1 ' Geograph. Journal,' vol. i. p. 170. 



