name. 



ARAVALLI SYSTEM. 9 



one region could hardly be asserted not to have come from any 

 other." 



There can be but little objection to the utilisation or re-applica- 

 tion of the old and hitherto vaguely defined 



Reason for a separate ^^ ()f AjftVaffi for these rocks * jf it be 



understood to be merely a means to an end, 

 the end being an intelligible description of the things themselves. 

 If there be anv real objection, it is likely to lnrk in the fact that 

 at the other end of the old Aravalli range in Rajputana the same 

 term is being contemporaneously applied to other extensions of 

 what are supposed to be the same system, but which, as time goes 

 on, may prove to be either somewhat more or somewhat less com- 

 prehensive than in my case. Should this eventually be shown to 

 be so, it may then be necessary to discard the use of the term Aravalli 

 as a moderately general term, and to rely on fresh local names 

 for all phases of the older crystalline complex that cannot certainly 

 be actually traced into, and manifestly correlated with, each other. 

 I believe nothing is gained by basing the general use of a wide classi- 

 ficatorv word on conjecture and surmise, or as a mere expression 

 of personal and often provisional opinion concerning widely separated 

 areas. For the time being the object sought in applying the local 

 name Aravalli to these rocks is merely to distinguish them from other 

 varieties and groupings of similar rocks elsewhere developed in India. 

 This seems a better policy than rashly to classify them as say 

 Dharwarian or anything else that would necessitate a speculative 

 mental leap, even though the guess might eventually turn out to 

 be a good one. 



Descriptive Details. 



The sub-headings under which sundry varietal and geographically 

 distinct members of this Aravalli facies will 



Subdivisions. i j 1 j i. • n 



now be described are categorically as 

 follows : — 



(1) Calc-gneiss of Vadali, Khed Brahma and Golwara areas; 



(2) Non-calcareous biotite-gneiss, associated with the calc- 



gneiss ; 



(3) Aplite and pegmatite veins intrusive in the calc-gneiss 



and biotite-gneiss ; 



(4) Origin of the calc-gneiss, biotite-gneiss and their plexus 



of aplite veins ; 



