74 wynne: geology of kutch. ^' '^ [paiit i.' 



Tertiary. 

 The rocks of this formation comprise several groups, each charac- 

 terised either by some petrological peculiarii;y or 

 ° ' by the prevalence of certain fossils. The whole for- 



mation isj however, subject to irregularities, very likely to mislead, and 

 not only are whole groups wanting in some parts of the area, but 

 individual beds vary along their extension, or die out altogether, so that 

 the sub-divisions to be just now described, though made with care, 

 are occasionally open to some amount of uncertainty. 



The beds present a large and varying series of alternations of shales 

 and clays with sands and sandstones, marly and 

 sandy aluminous beds, calcareous marlstones and 

 grits with conglomerates and gravels in the upper part of the series. 



The higher beds have but faint representatives in the western side 

 of the province, nor are the lower ones found to the east ; and as several 



local unconformities occur, and oblique lamination 



Local unconformity. . ■,,,■,-, t ■, ■ n i 



is very prevalent, the beds bemg generally nearly 



horizontal, it becomes a task of considerable difficulty to correlate the 

 evidence afforded by different distant sections so as to generalise with 

 regard to the whole formation. 



The marly and calcareous nummulitic beds occur near the base of 

 the series, between two zones of shaly rocks con- 

 taining fossil leaves of terrestrial plants. The lower 

 of these zones is closely associated with the upper beds of the sub-nummu- 

 litic group, so closely indeed that it is not easy to separate it from them. 

 The most fossiliferous deposits (excepting the nummulitic ones) are 

 found in the middle of the series ; and from the 

 fact of their being developed only in the west, it 

 may perhaps be inferred that the sea of that period did not extend 

 eastwards, the places in that direction where 

 '^ ' higher beds are now found not having been then . 



( 74 ) 



