chap. xiv. Section of the Uspallata Range. 525 



rather large coppery-brown crystals of an augitic mine- 

 ral. 1 Another variety was of a dull-red colour, having 

 a clay-stone brecciated basis, including specks of oxide 

 of iron and of calcareous spar, and amygdaloidal with 

 green earth : there were apparently several other 

 varieties. These submarine lavas often exhibit a sphe- 

 roidal, and sometimes an imperfect columnar structure : 

 their upper junctions are much more clearly defined 

 than their lower junctions ; but the latter are not so 

 much blended into the underlying sedimentary beds as 

 is the case in the eastern flank. On the crest and west- 

 ern flank of the range, the streams, viewed as a whole, 

 are mostly basaltic ; whilst those on the eastern side, 

 which stand lower in the series, are, as we have seen, 

 mostly feldspathic. 



The sedimentary strata alternating with the lavas 

 on the crest and western side, are of an almost infinitely 

 varying nature ; but a large proportion of them closely 

 resemble those already described on the eastern flank : 

 there are white and brown, indurated, easily fusible 

 tuffs, — some passing into pale blue and green senii- 

 porcellanic rocks, — others into brownish and purplish 

 sandstones and gritstones, often including grains of 

 quartz, — others into mudstone containing broken crys- 

 tals and particles of rock, and occasionally single large 

 pebbles. There was one stratum of a bright red, coarse, 

 volcanic gritstone ; another of conglomerate ; another 

 of a black, indurated, carbonaceous shale marked with 

 imperfect vegetable impressions ; this latter bed, which 

 was thin, rested on a submarine lava, and followed all 

 the considerable inequalities of its upper surface. Mr. 

 Miers states that coal has been found in this range. 

 Lastly, there was abed (like No. 10 on the eastern flank) 



1 Very easily fusible into a j et black bead, attracted by the magnet : 

 the crystals are too much tarnished to be measured by the goniometer. 



