1917.] The Fourth Indian Science Congress. cxcvii 



although since their formation they have been subjected to earth 

 mcvements which have acted on them both alike, and caused their 

 present disposition (as indicated by outcrops and foliation dips) to 

 be generally inconclusive one way or the other. 



Some few exposures (sections they can hardly be called) are, 

 however, so strongly in favour of the received views concerning 

 this relation that they must be mentioned here. Mr. Smith has des- 

 cribed, and I also myself saw, one locality in the valley N.N.W. of 

 Maharajgadi, where a certain flattening out of the Dharwars and a 

 bending round of their strike appeared to point to the existence of a 

 slightly shallow synclinal of them upon the gneiss. In another 

 locality a few miles east of Krishnagiri and a little west of Sundana- 

 palli Mr. Smith states that the exposure of the Dharwars seems to 

 be that of a rough basin resting on the gneiss though the dips are 

 seen to be much disturbed. Also round about Maradapalli the Dhar- 

 wars are seen to rest directly on the upturned gneiss. Other places 

 visited by myself to the north of Barugur show the same thing— in 

 the usual imperfect way in which sections are exposed in this part 

 of the country. T may instance the hill 1£ miles E. by N. from 

 the Barugur travellers' bungalow, the upper parts of which are all 

 Dharwars apparently resting on a platform of the gneiss beneath ; 

 and also an exposure north of Neralkotta where a somewhat sudden 

 change from the one rock to the other has all the appearance as 

 of the Dharwars lying upon the top of the gneiss. 



The search for actual junction sections was, however, for a long 

 time unproductive. At last the little crag on the side of the hill 

 E.N.E. of Barugur, and easily recognised in the distance by its darker 

 colour, yielded such a section : but we were not prepared for the ex- 

 traordinary nature of the section revealed. It is about 5 yards long, 

 and at the base of it the hornblende biotite gneiss, typical of the 

 Hosur and Krishnagiri plateaux, is seen. Above there are Dharwars 

 of the lower-most orepidiorite type, whilst between the two is a zone 

 composed of a matrix of the hornblende-biotite gneiss among which 

 is distributed an irregular assortment of fragments of Dharwars. 

 We might describe the arrangement as a zone of the gneiss containing 

 included blocks of the Dharwars. The fragments are of all sizes 

 from a few inches across to several feet. They are roughly angular, 

 and many of them are composite blocks, being built up of a number 

 of smaller fragments-the result without doubt of a large block 

 having split up into pie< 9 in situ. With everything else m favour of 

 the Dharwars being the younger formation, here is an appearance 

 that I think the majority of observers would say showed that the 

 intrusive gneiss was younger than the Dharwars ! 



But before committing ourselves to this last conclusion, let us sum 

 up the arguments for the contrary : 



( 1 ) The work of the older observers has been held to show that the 



Dharwars are a younger formation resting with complete 

 unconformity and a great conglomerate on the gneisses. 



(2) The Dharwars of the Salem District here referred to are directly 



continuous into those of Kolar, and must cartamly be the 



same. 



(3) The mode of occurrence of the Dharwars is as strips among the 



gneiss, not the reverse. Also there are no veins or vemlets 

 of the gneiss among the Dharwars. O : m ;i or 



(4) Almost universally in the gnei* there are long trams of s.mdar 



inclusions at other places where no bulky outcrop of Dhar 

 wars of sufficient magnitude to be mapped s known and 

 these trains of inclusions frequently coalesce moneor oth er 

 direction into unbroken strips ,n the gneiss of from 1 to 3 



feet wide. 



