DESCRIPTIVE GEOLOGY: SLATE ZONE, I? 1 



road crosses it by a wooden strut-bridge at a height of about 60 feet, 

 The gorge meanders along the outcrop of the Grey limestone and 

 Jura-Cretaceous, and in so doing crosses several times at different 

 places both of the faults on each side of the wedge of these rocks 

 before reaching Tirati where the stream divides. The hill just south 

 of the " 1 " of Malsuh shews that the Trias has again returned to its 

 normal position in contact with the slates, both series being practi- 

 cally vertical, and much folded in extended isoclinal folds. We may 

 assume, therefore, that the narrow wedge of Grey limestone and Jura- 

 Cretaceous rocks along which we traversed has come to an end by 

 the junction and dying-out cf the two nearly parallel faults Avhich 

 bounded it. The stream section above Tirati is, however, far from 

 clear as to the details of the process. 



From the last position at the north-eastern end of the wedge of 



„ . , Grey limestone, the hill-side above to the north-west 



Section from 



near Phulkot shews, by the presence of a village among dark-coloured 

 toSirbunnuh. 



fields a little east or the "g of Uzeezmung, that there 



is a sharp fold of the Spiti shales among the Trias on the slope. 

 Travelling up across this ridge via Malsuh, and across the interven- 

 ing ridges and spurs to Sirbunnuh, we pass over sections which may 

 be summarised in the sketch-section which follows. The pathway 

 along which my party travelled is a steep and difficult one, our laden 

 mules only with the greatest trouble being able to pass some of the 

 rotten disintegrating spurs of slate. Comparing the section below 

 with the structure of the hill south of Uzeezmung, as depicted in 

 horizontal section No. 2, we see that the contorted and peculiar 

 folding of the Trias and superincumbent rocks of that hill are 

 replaced in that section by some very pretty examples of faulted 

 sigmaflexures, involving all the rocks in stratigraphical sequence 

 from the slates to the Spiti shales. To follow out the change the 

 map must be consulted in conjunction with the sections. It will 

 then be seen that the Supra-Trizs rocks, south of Uzeezmung, are 

 in the form of an irregularly elliptical outlier. The Grey limestone 

 forms the top of the main ridge as far as the " B " of Bhungoor, 



( I7i ) 



