42 MIDDLKMISS : THE GEOLOGY OF IDAR STATE. 



swamy (Geol. Mag., August 1901), have some similarities, especi- 

 ally in their mode of occurrence as narrow and often lenticular 

 masses cutting disordantly across the foliation of the charnockite 

 series and in the diverse nature of the dark minerals present. The 

 occurrence of allanite granite as one member of this series is note- 

 worthy, and in particular the reference {he. cit. p. 421) to the 

 allanite as " forming a centre for radiating cracks in the rock giving 

 it a rather conspicuous appearance "- — which agrees with my own 

 observations of the allanite in £?<> (12331) and 4 \\ (12332) (see p 40). 



(4) Origin of the Calc-gneiss, Biotite-gneiss and their Plexus of Aplite 



Veins. 



Before proceeding to the description of the neighbouring Kherod 

 series of metamorphic limestone and amphibolite, and before passing 

 to the other more distant and disconnected members of the great 

 Aravalli complex, it will be well to clarify our conception of the 

 series so far described by considering the question of their genesis, 

 in so far as this is in any way involved with, or inspired by, the 

 foregoing descriptions of them. 



From some of the leading features already alluded to in 



the preliminary remarks on the Aravalli s 



No evidence of a scdi- ag a W ] U) ] 0) anc i f rom the facts of structure 



mentary Ongm. , . , , , 



and composition of the calc-gneiss already 

 presented in some detail in a previous section, it is clear that the 

 latter in its present highly crystalline, foliated state reveals no 

 indisputable evidence of a sedimentary or clastic origin ; exposes 

 no lithological sequence that might be regarded as dimly corre- 

 sponding to a varying set of beds formed like modern calcareous, 

 argillaceous and arenaceous deposits. We cannot point to any 

 conglomerate, any waterworn or water-distributed material, any 

 bedded, false-bedded or interbedded arrangement of such material 

 and of course no trace of organic remains. If, therefore, the calc- 

 gneiss series in its ultimate and original state was deposited by 

 any process akin to present-day sedimentation, we must acknow- 

 ledge that all signs of such a process have been obliterated, and the 

 whole of the material rearranged molecularly into fresh and often 

 new mineral forms. 



It must of course be conceded that the large amount of general 

 evidence bearing on the metamorphism of known sedimentary 



