CHAP. 7.] ROCK FORMATIONS. SUB-NUMMULITIC. 73 



Jurassic rocks; and unless these lateiites themselves represent some 

 variety of volcanic 'derivate' rock, the source of the agates rather 

 widely disseminated in them is somewhat mysterious, there being no 

 evidence that the bedded traps ever existed in that part of the dis- 

 trict, nor does any outlier of them occur within a distance of about 

 forty miles. 



That the lower tertiary beds in both regions represent the same 

 period is more than probable, both being characterised by the presence 

 of a nummulitic group and other tertiary fossils, many of which will 

 doubtless prove to be the same, and both containing interbedded laterites. 

 Below all these there is some slight evidence of the re-appearance in 

 Gujrat of the Kutch sub-tertiary group ,• but this is weakened by so 

 little being seen, and their derivative character, with other appearances of 

 unconformity between these Gujrat traps and tertiaries, still presents a 

 difficulty in reconciling the general features of the two regions. 



It seems possible that in so vast a trappean area as that of Western 

 India, the volcanic activity may not have been everywhere contem- 

 poraneous, and that some of the Gujrat traps may have been subjected 

 to denudation before the close of the eruptive period in the Kutch area. 

 The last-eruptions of unusually ferruginous and earthy lavas may have 

 been subaqueous, if not submarine or only partially terrestrial, and rivers 

 from the neighbouring land may have brought down the dicotyledonous 

 and other leaves to be mingled with, and have their forms preserved in, 

 strata perhaps largely made up of re-arranged volcanic mud. 



Similar eruptions may have simultaneously occurred in the Gujrat 

 direction, the relations being less perfectly seen ; or the denudation 

 of the traps may have commenced at a somewhat later period than 

 has been supposed, the uppermost traps of Kutch then remaining sub- 

 merged, or at least the portions which formed the land being now 

 untraceable. 



k ( 73 ) 



