SUPERFICIAL DEPOSITS IN CUTCH. dll 



(3) INFRATRAPPEAN GRITS. 



These deposits, lying as they do below the traps, cannot in strictness be called 

 superficial, but it will be seen that they were probably of that character — 

 that is, deposited on the land before the traps were poured on the top of 

 them. This is what Mr. Wynne says of them: — " These form a peculiar, soft, 

 loosely granular, and obscurely stratified group of earthy and sandy rocks, 

 largely composed of trappean materials . , [they] are frequently associated 

 with the base of the stratified traps, but they also occur in separate patches 

 over the country, and sometimes at a considerable distance from them. They 

 are clearly beneath the trap in some localities ; in others they fill up hollows 

 in the Jurassic beds, the planes of stratification not being conformable even 

 to the surfaces of the hollows which they occupy,"! 



In the detailed description, however, I can find only eight places where 

 they are recorded, namely, west of Bhachau, Bhujia Hill, two places north of 

 Katrod, Rhojla Bill, " Khirgreea," Rampur, and Lakhapur, The letter d by 

 which they are indicated is also marked on the map at Sanosra and west of 

 Mundhan, Of these, one of the localities obviously represents, by the descrip- 

 tion, some fault-rock only ; that at Lakhapur and west of Mundhan is related 

 to an intrusive mass of igneous rock which the deposits do not underlie, but 

 merely abut against, so that they may possibly belong to the subrecent 

 concrete. Of the deposit at Rampur, it is stated that " it may have been the 

 basal portion of the trap series," It is not connected with the trap of the 

 neighbourhood, and consists of " scoriaceous lumps of trap mixed with sand " 

 etc., so that this also may be an old variety of subrecent concrete. Of the 

 other deposit north of Katrod, we read that beneath the trap is " a hard bed 

 of black ferruginous grit ;" it therefore contains no trap-fragments, and may 

 perhaps be dismissed as doubtful. There remain therefore five spots where 

 peculiar deposits are actually found below the traps, with a sixth 

 at Artara, unrecorded by Mr. Wynne, and in no case are they large 

 enough to map .2 



These six may also be grouped together, for those at Artara and at Sanosra 

 are of the same character, and those at Khirgreea and Bhojla Hills are 

 described as similar to that at Bhujia Hill. There are thus, with that west of 

 Bhachau, three types of such deposits, 



I have thought it necessary to thus analyse the evidence on account of the 

 statement that they are " largely composed of trappean materials," which 

 is difficult to understand if they are infra and therefore presumably 

 pre-trappean. 



1. Mem. Geol. Surr. India, vol. ix. 1 1. i ( 1872) , p. 56, 



?. On Mr. Wynne's map there is marked a considerable expanse of iufratrappean rocks in 

 the neighbourhood of Bhachau, but there is evidently something wrong here. A distinct 

 unexplained colour is inserted, and the details do not correspond with the text. Moreover' 

 the deposits are not overlain by the traps. 



