RESULTS. 177 



Elevation of sea floor. — As the subaqueous tuffs are abruptly 

 overlaid by clearly subaerial volcanics, we must infer that, at least 

 locally, an elevation of the sea floor has taken place, and this would 

 point to the sedimentary beds having for some time been subject to 

 subaerial denudation. 



Subaerial denudation, previous to volcanic outbursts. — As regards 

 the latter, I must confess that no conclusive evidence is available, but 

 the absence of the tuffs (4/) in the sections south of the Kiogarh high 

 plateau is no doubt an argument of some weight. Mr. Griesbach's 

 map of the Chirchun area further shows in two places igneous rocks 

 overlapping the flysch and the Spiti shales, a feature which would be 

 perfectly congruous with denudation, preceding the outburst of the 

 valcanoes. 



Later disturbances. — As stated above the volcanic outbursts 

 were followed by disturbances. These are the more intense the farther 

 south-east we go, and this fact can be accounted for by a change in the 

 strike. 1 



To the north-west of Laptal, there is a broad, slightly disturbed 

 belt of Spiti shales and flysch striking north-west to south-east. This 

 belt becomes gradually much narrower and more complicated further 

 south- east, the strike changing to north-south, and it ends within the 

 corner described by the boundaries of Dharrna, Johar and Hundes. 8 

 Thus the Spiti shales dwindle down to narrow strips and the triasso- 

 jurassic anticline appears, while the structure of the flysch gets 

 gradually complicated. At the same time there appears in Hundes 

 the anticline of the Chanambaniali peaks, as a counterpart of the 

 anticline of the Lahur. 



Effect on volcanics. — These disturbances have affected the volcanics 

 too, but only in the south-east corner of the belt. In the neighbour- 

 hood of the Balchdhura heights they were of too small an intensity to 

 have any perceptible effect on the volcanics, while the thick and rigid 

 masses of the Kiogarh high plateau appear to have resisted a pressure 

 that caused great complications in its more easily yielding flysch base. 



1 See al?o Griesbach, Memoirs, XXIII, and Diener. Ergebnisse, p. 604. 



2 See geological map in Griesbach, Memoirs, XXIII. 



( 5' ) 



