GENERAL DESCRIPTION OF AREA AND ROCKS. 11 



however, that such thoroughly metamorphic strata should normally 

 overlie those in a less altered condition, the evidence points to this 

 conclusion. 



From Karsiang to Darjiling the gneiss is continuous, verging in some 

 places towards mica-schist. The Darjiling gneiss generally, in fact, has 

 a great tendency to graduate into the latter lithological type. The dips 

 are uncertain and irregular, with several local anti- and syn-clinals, but 

 on the whole, are northerly near Karsiang and southerly near Darjiling. 

 As we descend the spurs towards the Ramman, the slates are found 

 again underlying towards the gneiss, but, in places at least, the boundary 

 between the two series is a faulted one. The fault may be continuous, 

 but I believe that the throw is not very great, and that it has merely 

 complicated a line of junction along which the slates underlie the more 

 metamorphic strata. 



If we followed the ill-marked, and often indefinite, boundary between 

 the slates and gneiss, down the valley of the Tista, and thence back 

 to Karsiang and on to the Mechi, we find that the underlie of the 

 former is a constant feature. The same thing occurs east of the Tista 

 also. From the Jaldoka, by Daling, round to Damsang, wherever I 

 crossed from one series to the other, the inclination is towards the gneiss. 

 The Pre-tertiary rocks on both sides of the Tista, may be regarded as 

 belonging to one rather shallow synclinal (including within itself many 

 minor folds), the axis of which is somewhat raised near the river by a 

 secondary anticlinal at right angles to the synclinal. The lower rocks 

 are in consequence of this elevation brought to the surface, and are more 

 fully exposed than they otherwise would be, on account of being cut 

 through by the deep transverse valley of the Tista. The elevation is 

 not sufficient to bring the Damiidas to the surface along the valley, 

 and these rocks are consequently only exposed along the southern 

 edge of the synclinal, where they outcrop in a narrow band varying from 

 200 or 300 yards to about a mile in width, and extending from 



( ii ) 



