162 NERBUPDA DISTRICT. 



Thick massive sandstone, white, and in all respects like that above 

 described at the top of the section. 



From a study of these sections a tolerably correct idea of the litholo- 



Remarks on the above £ ical characters and of the formation may be 



sections. gathered, the sections given having been selected 



as typical. The rocks enumerated are those which are included under 



the sub-divisions d, e, and/ (namely the lower Damuda) of our list. 



It is interesting, and indeed very important, to obtain some reliable 



Estimated thickness of estiraate of the thickness of this portion of the 

 the lower Damuda. serieg . for it i llc i U( Jes all the really valuable coal 



of the country, and many of its shales abound in fossil remains. Most of 

 it is sufficiently clearly bedded to afford satisfactory measurement of dip, 

 so that the difficulties met with in estimating the thickness of the Tal- 

 cheer group no longer exist here ; but others unfortunately occur, some 

 attempt to meet which must now be made. 

 It will have been remarked in looking over the above sections that both 

 Difficilt' •' bl ^ ie amoun * ana< direction of the dip is variable wit'h- 



aracter. in very short distances, indeed the dip is very rare- 



ly so constant as in the sections noted, and is very often inverted several 

 times within far shorter distances. As a rule the beds roll ; the curves 

 of the anticlinals and synclinals being sometimes very sharp, this is the 

 first obstacle encountered when an estimate of the thickness is attempted. 

 The next consists in the numerous faults everywhere found, some- 

 times these are so exposed as to shew on which 

 Number of faults. 



side the downthrow occurs; sometimes even the 



amount may be fairly estimated if not actually measured ; but the 

 commonest case is that in which the existence of the fault is indicated by 

 a line of fault rock (a breccia which will be more fully noticed hereafter) 

 where, from the very nature of the action which has affected the beds at 

 the line of fracture, the identification of any of these, at opposite sides of 

 the break, is generally very unsatisfactory. 



