ARAVALLI SYSTEM. 7 



of India that they are generally hidden under a thick mantle of 

 Recent sediments, from beneath which their outcrops are only 

 here and there discernible as isolated patches, and in occasional 

 stream-beds. 



Another general feature of this Aravalli complex that had 

 better be referred to now is that which is 



No serial order (lis- , ,. , , . . ,. , . 



cerniblc in the com- implied by the expression complex. Locally 

 P lex - one may easily detect small series and sequences, 



but as a whole one cannot certainly predicate any serial order for 

 the whole set. There is no recognisable top, middle or bottom to 

 the Aravalli svstein as a whole. When later on we come to discuss 

 the remaining less ancient formations present in idar in their 

 relation to these underlying Aravallis, namely, the Delhi Quartzite 

 and the Phyllite System or Series, it will be found a task of no 

 small difficulty to establish conclusively even their order of super- 

 position. Intimate deformation of the finer structure, shearing, and 

 differential slipping of platy layers over one another in consequence 

 of deep-seated earth stresses that must have operated very low 

 down among this ancient Aravalli mountain range, can frequently 

 be shown to have seriously blurred the lines of ordinary sedimenta- 

 tion, even in such resistant material as Delhi Quartzite. Much 

 more so then must we be prepared to find the task of unravelling 

 the complicated banding and foliation of the underlying Aravalli 

 schists to be even more difficult or impossible. We cannot tell 

 exactly how these mineralised formations have responded to the 

 presumably intense earth stresses brought to bear upon them. The 

 comparatively simple appearance of their foliation planes dipping 

 steadilv in one direction or bent into anticlines or synclines almost 

 certainly does not express their full history, which most likely has 

 been much more involved, and it may be necessary to contemplate 

 the existence of a zone of rocks on which has been superinduced 

 deformation by flowage (rock flow) producing gneissic foliation and 

 mineral banding that simulates original bedding. 



Hence one is compelled to describe the Aravallis as a complex 

 having here and there in patches certain serial orders of banding, 

 but we are entirely unable to unravel their now hopelessly blurred 

 folds, and arrange them in a definite sequence of strata having a 

 proper superpositional order among themselves. 



The same impedimenta in the way of visualising the folds and 

 sequences of this complex also prevent us from gauging its total 



