68 MIDDLEM1SS: PHYSICAL GEOLOGY OF SUB-HIMALAYA. 



wards the south-east in the direction of the Gaujera Rati this fault 

 appears to die out. 



The sand-rock stage in the PeMni is now left behind. Nothing 

 but Nahan sandstone intervenes between this point and the main 

 boundary. The folds into which the Nahans are thrown, however, 

 can be better seen in the section than described in words. Generally 

 the result is a great synclinal, with lesser secondary folds borne on 

 it. At the centre of the section the rock is evidently very near the 

 top of the Nahan stage, from the greater softness of the rock and its 

 appearance of being about to pass into the sand-rock stage. At the 

 main boundary fault the strata are neither uppermost nor lowermost 

 Nahans, but their horizon seems to be intermediate. A marked fea- 

 ture of this Nahan zone is the greater folding to which the strata have 

 been subjected, together with the inverted state of many of the folds, 

 which gives an appearance at first as if the whole were an ascending 

 series in one direction. In many respects it can be seen to be analo- 

 gous, in its folds, to the structure already noticed in the Gaujera and 

 Delidunga Raus. 



We have now reached the main boundary fault once more. The 

 Pelani R. cuts through a steeper and higher set of hills than hereto- 

 fore, which marks the in-coming of the mesozoic, nummulitic and 

 Himalayan zones. As being a very illustrative section, therefore, 

 I shall continue the description up the Pelctni R. ; for, although 

 I shall thereby be trenching somewhat on a subject foreign to the 

 matter of this memoir, I hope the better to exhibit the true status of 

 the Sub-Himalayan zone by comparing it with those older zones. 



A few remarks may be made upon the surface features of the 

 country to the north of the main boundary. The change from the 

 low-lying ground of the Sub-Himalaya to the much higher ranges 

 to the north is very apparent. We lose for ever those flat and 

 undulating duns and chaors which so characterise the zone of younger 

 formations. With the change in the nature of the rock there fol- 

 lows a change in that of the soil, and in the vegetable products 

 of the soil. The jungles lose their depth and vastness, and their 

 tropical characteristics seem to give way with magical abruptness. 

 ( 126 ) 



