524 Section of the Uspallata Range, paeth. 



lines in a less perfectly characterised variety. I have 

 much difficulty in believing that this thin layer of 

 pitchstone flowed as lava. 



Eleventhly : sedimentary and tufaceous beds as 

 before, passing into sandstone, including some con- 

 glomerate : the pebbles in the latter are of clay-stone 

 porphyry, well rounded, and some as large as cricket- 

 balls. 



Twelf thly : a bed of compact, sonorous, feldspathic 

 lava, like that of bed No. 8, divided by numerous joints 

 into large angular blocks. 



Thirteenthly : sedimentary beds as before. Four- 

 teenthly : a thick bed of greenish or grayish black, 

 compact basalt (fusing into a black enamel), with small 

 crystals, occasionally distinguishable, of feldspar and 

 augite : the junction with the underlying sedimentary 

 bed, differently from that in most of the foregoing 

 streams, here was quite distinct : — the lava and tufaceous 

 matter preserving their perfect characters within two 

 inches of each other. This rock closely resembles 

 certain parts of that varied and singular lava-stream 

 No. 6 ; it likewise resembles, as we shall immediately 

 see, many of the great upper beds on the western flank 

 and on the summit of this range. 



The pile of strata here described attains a great 

 thickness ; and above the last-mentioned volcanic stra- 

 tum, there were several other great tufaceous beds 

 alternating with submarine lavas, which I had not time 

 to examine ; but a corresponding series, several thou- 

 sand feet in thickness, is well exhibited on the crest 

 and western flank of the range. Most of the lava- 

 streams on the western side are of a jet-black colour 

 and basaltic nature ; they are either compact and 

 fine-grained, including minute crystals of augite and 

 feldspar, or they are coarse-grained and abound with 



