2 GEOLOGY OF THE SON VALLEY, ETC, 



and the resulting memoir suffers from the drawback of being a 

 compilation from the work of a number of men who have each 

 surveyed different portions of the area. In 1894 the survey having 

 been put into my charge, I had not only to re-survey a portion of 

 the area, but also made several tours of the region for the express 

 purpose of linking up, so far as possible, the work of other officers of 

 the survey. 



On the map accompanying this memoir the geology of the part 

 comprised in Rewah State is exclusively based on the recent surveys. 

 In Mirzapur the boundary of the lower Vindhyans was re-surveyed 

 by Mr. Vredenburg in 1895-96, but with this exception, and some 

 modifications mentioned in the text, the geological outlines are 

 taken from the old surveys. West of Rewah the country has not 

 been revisited and the old surveys have been incorporated. Very 

 little reference will be found in the following pages to the area 

 covered by the map outside Rewah State, but its incorporation 

 in the map was considered advisable in order to complete the 

 geological features which would have been but imperfectly ex- 

 hibited if the map had been strictly confined to Rewah territory. 



Of previous published accounts of this area there are very few. 



„ . For the earlier ones reference may be made to 



Previous accounts. J 



Mr. Mallet's memoir 1 published in 1869. Since 

 that date the only published statements regarding the region dealt 

 with in this memoir are to be found in the Records of the Geological 

 Survey of India. 



An analysis of Galena, 2 a description by Mr. T. H. Holland of 

 some rocks collected by Mr. P. N. Bose 8 and three analyses of iron 

 ore 4 are printed in the lists of assays and examinations made in the 

 laboratory of the Geological Survey. Some specimens of norites from 

 this area are described in a paper by the same author in Vol. XXX, 

 of the Records, Geological Survey of India, pp. 16-42. 



1 Mem.. Geol. Surv. Ind., Vol VII., pt. i. 



2 Rec, Geol. Surv. Ind., Vol XXVI., p. 109. 



a Rec, Geol. Surv. Ind., Vol XXVII., p. i 4 g. 

 4 Rec, Geol. Surv. Ind., Vol XXX., p. 256. 

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