LOWER VINDHYAN SERFES. 99 



Vindhyans and the Gondwanas becomes rapidly narrower, so that the 

 chances of discovering these dykes become proportionally less. 

 Eastwards, the Archaean and all the other rocks become greatly 

 concealed by alluvium and have not been studied in detail. My own 

 work did not extend so far east as the Koel river. But in the Survey 

 collection there exist specimens of " trappoids M from the district 

 east of that river, and these proved on microscopical examination to 

 be true igneous rocks. 



The exposures from which these specimens have been derived 

 p ., L occur south-east of Rotasgurh, or more exactly 



exposures near Kutum- ° J 



beh. south of Kutumbeh (Lat. 24 37', Long. 84 17"). 



Here the trappoids are described as resting immediately upon the 

 gneiss, and consequently the lowermost divisions of the series are 

 stated in previous publications to be missing ; " In the outliers, 

 however, which occur in the alluvium south-east of Rotasgurh, the 

 conglomerate is entirely absent, as well as the next two members 

 of the series, and beds, apparently representing the trappoid band 

 No. 4, rest directly on the crystalline rocks " (Memoirs, Vol. VII, 

 page 32 ; the same statement is again made on page 36). I may 

 just mention that this observation does not necessarily entail the 

 disappearance of the stages 1, 2 and 3 by an overlap o f No. 4, 

 The band No. 4 corresponds to the pe;iod of maximum deposition of 

 the " trappoids," but it has been ascertained they occur at intervals, 

 both above and below that horizon, and are often fairly abundant 

 towards the base of the series. Moreover, as will be shown here- 

 after, these Kutumbeh rocks are most probably of the nature of 

 intrusive sills, and would be newer, therefore, than the horizon to 

 which they appear to belong. 



This is how Mr. Medlicott describes one of these occurrences in his 



Rocks described by P ™gress Report of 1863-64 : " I will now notice 

 Mr. Medlicott. this felspathic Son rock in its extreme form. 



Last season (63-64), in working along the crystalline boundary from 

 the east, I was awfully puzzled when I came to the Kalapahars — a 

 very conspicuous and remarkable group of dome hills South of 

 Kootoombeh, These complete domes are formed of the most 



H 2 ( 99 ) 



