28 MEDDLEMISSj THE GBOLOGI OF TDAR STATE. 



Without entering here into any elaborate discussion of the 



r phenomena just presented, the description mav 

 Eruptive unoonior- * * . * , 



mity or /.one of plaatio halt for a moment to point out that it seems 

 deformation indicated. c j ear ^at t | 10 j un( . t j (m described is not a case 



of simple unconformity of the visible base of the Delhi Quartzite 

 on the biotite-gneiss. The foundered blocks of the former, which 

 appear to have been stoped away and engulfed among the biotite- 

 gneiss, and the contact minerals developed in them and also in 

 the lower visible but undetaehed masses of the Delhi Quartzite, 

 undoubtedly indicate that the plane of junction is of the nature 

 of an eruptive unconformity, or of one due to plastic deformation 

 in a zone of rock llowage. as contrasted with ordinary shearing 

 with cataclastic structures which do not appear. 1 The Delhi 

 Quartzite blocks in the gneiss never show any sign of deforma- 

 tion or rolling out in themselves nor any form of shearing. They 

 are just irregular blocks that, so far as their internal evidence goes, 

 might equal! v well have been xenoliths torn ofi by ordinary 

 igneous action. 2 



Continuing the description of these eastern outcrops, the steep 



little knoll just E.S.E. of Dijio and across 



Knoll E.S.E. of |j lc s tr C am, exposes a fringe of the biotite- 



I >IJ 10. . 11- 



gneiss at the base; and above it, occupying 

 the knoll, its junction representative as regards the Delhi Quartzite, 

 is a rather peculiar quartzite, £fo (1 2291 ), coarser than usual with 

 a sprinkling of biotite, a little white mica and some isolated 

 grains of orthoclase and microcline. All the beds dip rather 

 steeply at about 45° to E.S.E. In the next lower knoll to the 

 east, ordinary Delhi Quartzite of the usual type makes its 

 appearance (^A). It is conceivable that the coarser quartzite of 

 the first knoll may represent a basal variety of the Delhi Quartzite, 

 but all evidence of original clastic structure has disappeared. No 

 wollastonite, garnet or diopside are seen. All the quartz is very 

 dusty with inclusions. There is only a trace of iron ore. 



These formations then disappear under alluvium for a few miles, 



their next exposure being 1 mile north of 



Derol, where a low little platform of the 



Delhi Quartzite is partially surrounded by a rim of the biotite- 



1 See Mem., Geol. Sitrv. Ot. Britain, Structure <>f X. W. Highlands, I DOT, p. 598. 

 - The author lias recently (1916) seen even more striking discordances of this nature 

 in Aimer between the Pelbi Quartzite of that area ami the underlying calo-gneisses, 



