VI NOTICE. 



In issuing a very detailed report, such as the present, it seems desir- 

 able to draw attention to the essential difference which characterizes 

 the labours of the Geological Survey of India in different districts : a 

 difference fully exemplified in the nature and amount of detail of the 

 several reports published in these Memoirs. In some cases, a compli- 

 cated structure, and richly fossiliferous rocks may occur in districts of 

 which topographical maps exist on such a scale as will admit of a 

 large amount of details being recorded with accuracy: in other cases 

 either the merest sketch, or perhaps no map whatever, can be procured. 

 And we have more than once been compelled to construct as rapidly as 

 possible such a topographical sketch as could be carried on without 

 serious delay in the field, and as would suffice to indicate rather than 

 record the Geological observations. Of these two cases, the districts of 

 the Nerbudda mapped topographically as well as geological!}'- by 

 Mr. Jos. G. Medlicott on the one hand ; and the Raniganj Coal- Field 

 and the Cretaceous district now published, on the other hand, may serve 

 as fitting examples. 



In the one case, no further expenditure of time was permitted, 

 than sufficed to obtain a general knowledge of the main features 

 of the structure of the district ; while in the other the fullest 

 and most detailed investigation was given, and such detailed maps 

 and reports as the following are the result. If we consider merely 

 the area examined, as compared with the time devoted to it, the 

 rate of progress in the one case was not one-fiftieth of that in the 

 other. 



In justice, therefore, to the writers of the several reports in these 

 Memoirs, this essential difference ought to be borne in mind, as showing 

 that the sketchy outline of general effects in the one case and the 

 minute and careful working out of the details of the picture in the 

 other, are simply the xniavoidable consequence of the different circum- 

 stances under which they were placed. 



