522 Section of the Uspallata Range. paeth. 



hundred feet in thickness are superimposed, varying 

 much in nature in short distances : the commonest 

 variety is a white, much indurated tuff, sometimes 

 slightly calcareous, with ferruginous spots and water- 

 lines, often passing into whitish or purplish compact, 

 fine-grained grit or sandstones ; other varieties become 

 semi-porcellanic, and tinted faint green or blue ; others 

 pass into an indurated shale : most of these varieties 

 are easily fusible. 



Fourthly : a bed, about 100 feet thick, of a compact, 

 partially columnar, pale-gray, feldspathic lava, stained 

 with iron, including very numerous crystals of opaque 

 feldspar, and with some crystallised and disseminated 

 calcareous matter. The tufaceous stratum on which 

 this feldspathic lava rests is much hardened, stained 

 purple, and has a spherico-concretionary structure; 

 it here contains a good many pebbles of clay-stone 

 porphyry. 



Fifthly : thin beds, 400 feet in thickness, varying 

 much in nature, consisting of white and ferruginous 

 tuffs, in some parts having a concretionary structure, in 

 others containing rounded grains and a few pebbles of 

 quartz; also passing into hard gritstones and into 

 greenish mudstones : there is, also, much of a bluish- 

 gray and green semi-porcellanic stone. 



Sixthly : a volcanic stratum, 250 feet in thickness, 

 of so varying a nature that I do not believe a score of 

 specimens would show all the varieties ; much is highly 

 amygdaloidal, much compact; there are greenish, 

 blackish, purplish, and gray varieties, rarely including 

 crvstals of green augite and miuute acicular ones of 

 feldspar, but often crystals and amygdaloidal masses of 

 white, red, and black carbonate of lime. Some of the 

 blackish varieties of this rock have a conchoidal fracture 

 and resemble basalt : others have an irregular fracture. 



