4G MEDDLEMIBS: TTIK GHBOLOGS OF EDAB STATE. 



and structural reconstitution necessary to provide, not only the calc- 

 crneiss of to-day in all its slightly varying forms, but also the biotitc- 

 gneiss and the peculiar stoped contacts with inclusions m it oi the 



Delhi quartzite. 



If this be granted, we migbt even go further and regard the 

 subsequently intruded plexus of aplite veins as also explained on 

 some such 'hypothesis as Lane's "selective solution " or dillerential 

 fusion theory (quoted in Daly's " Igneous Rocks and their Origin, }>• 

 370). which is as follows :— 



"During intense regional metamorphism, especially of the dynamic kind. 

 deep-seated rocks, charged with much interstitial water, may reach tin- relatively 

 low temperature at which minerals corresponding to the quarf/.-fc spar eutect ic 

 go into solution with the water and other volatile Buses. Such small locally gene- 

 rated pockets, lenses or tongues of fluid may be driven through the solid country 

 rock for an indefinite distance; subsequently to crystallise with the composition 

 and habit of the true batholithic derivatives. It is thus quite possible that these 

 particular rocks, though truly magmatic. have had no direct connection with abys- 

 sal injections." 



The same hypothesis would also help to explain the appearance 

 of partial interchange of material between the aplites and the 

 intruded calc-gneiss. 



In the few remarks above I bave confined myself to what may 

 be regarded as plausible, general hypotheses 

 Details of the prob- t() accoun t for the chief features of the local 

 lemstillUckmp - problem, on the basis of the rocks being 



essentially, and at first hand a sedimentary series. In describing 

 in a later section (see p. 53) the Mundeti series, distant some 

 8 miles away from the nearest outcrops of the calc-gne.ss, it 

 will be shown that they offer pertinent evidence making this funda- 

 mental assumption highly probable. At the same time it should 

 be noted that none of the problems regarding the detailed history 

 and order of development of the calc-gneiss minerals from such a 

 sedimentary series have yet been directly touched upon. 



It will be well for a moment to see how these local results compare 



with others recently expressed. The larger 



Views of Fermor and an( j m0 re general problem of the calc-gneisses 



^ urton - as a whole is one that has recently attracted 



much attention, not onlv in Tndia. where my colleague Dr. Fermor 



has gone very systematically into the question, 1 but elsewhere, as 



1 L Choi Surv India, Vol. XXXIII, pt. 3, pp. 108-171, (1000); also Mem , 

 G.S I ! Vol XXXVII. p. 299, (1909), and oJL Rep., &S.L, for 19U, Kec, G.8.I., Vol. 

 XLV.'p. 2. 



