DELHI QUARTZITE SERIES. 75 



(see p. 115), there remains principally a set of steep, fairly 

 elevated and connected ridges lying generally to the north and 

 east of the State. They show up prominently against the 

 horizon, as seen from the south and south-west, and appear to 

 form chains of hill-ranges whose mean elevation lies at a higher 

 level than that of most of the Aravallis. The Delhi Quartzite 

 constitutes these ridges. Its sudden appearance at its western 

 margin of outcrop, where it overlooks the plains and the 

 undulating country of Aravalli rocks, gives the immediate impres- 

 sion of a formation sharply contrasting with anything that the 

 Aravallis present, and implying a discordance of some sort on a 

 grand scale. 



Although simplicity in the details of its lie and structure (as will 



Its simple appear- presently be explained) is very far from 



anco at variance with characterising these elevated ranges, they 



detailed structure. n , , . . 



appear at first as though they might consist 

 of capping outliers of a younger more massive formation succeed- 

 ing unconformably upon the lower-placed Aravalli. This impression 

 is so strong that when afterwards one finds no sign of long, winding 

 scarps of nearly horizontal strata, such as are typical of forma- 

 tions like the Upper Vindhyan, the Cuddapah and the Deccan 

 Trap ; and when at the same time one is confronted with a 

 chaos of quartzite rock showing either no bedding at all or one 

 that seems often to plunge irregularly among the Aravalli 

 " setting " with steeply inclined dips, it would certainly be a relief 

 to be able to accept some theory by which a once nearly horizontal 

 mass of these coarse overlying sedimentaries had been reduced to 

 a condition of partial disruption and engulfnient of great descending 

 portions of it among a semi-plastic basement of Aravalli rocks, 

 rather than that the strata forming them had been folded, packed 

 and piled up on a solid Aravalli floor in normal, inverted or recum- 

 bent folds after the pattern of the younger mountain systems — such 

 as for instance the younger Himalayan zones. We shall return to 

 this point later. 



One of the most striking and tantalising features of Idar State 

 is the fact that the Delhi Quartzite is seldom 



Junction exposures r i • 1 i • 



generally bidden! iound in actual exposures lying on, or m 



direct contact with, any well-developed 



sequence of the Aravalli system— the stoped contacts with the 



biotite-gneiss as described on p. 26 being exceptional. In this 



