380 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol. XII. 



the Nerbudda Valley near Surat, as the only laterites which lie below well- 

 defined marine deposits. 



That there are lateritic beds below and associated with the Nummulitic 

 series in Cutch admits of no dispute; but those whose age can thus be prov- 

 ed all lie on the south side of the trap-escarpment and rest immediately on 

 the trap itself, where there can be little doubt that the lower red earthy 

 varieties are the products of decomposition in situ. It is with an entirely 

 distinct area that I am concerned, where the laterite is separated from the 

 trap by miles of intervening Jurassic rocks and Ran, and is overlain by 

 nothing but alluvium. That these also are sub-Nummulitic depends on the 

 assumption that all the lateritic deposits in a province as large as Cutch must 

 necessarily be of the same age — an assumption which does not appear to 

 me to be warranted. 



The superficial group of laterite is found only on the southern and west- 

 ern margins of the Ean islands and along the northern border (and eastern 

 also according to Mr. Wynne) of Wagir. In the course of this range it is 

 found lying on various members of the Jurassic series. In the north of 

 Patcham it lies on the oldest, in the north of Wagir on the youngest, and on 

 intervening members at other places. 



This distribution indicates, I think, a later age than the Nummulitic rocks, 

 for these latter rest upon the decomposition products of the trap, which do 

 not require long to form, and they nowhere extend to the Jurassic rocks, as 

 they surely must have done, if these had been already denuded to any great 

 extent. Whereas, before these laterites were produced, not only must the 

 lowest Jurassics have been exposed by denudation, but the general contour of 

 the country have been not far different from what it is at present. The 

 only indication of age that I can quote is that they underlie the boulder-beds 

 in Patcham, 



The laterite here is a sort of gravelly deposit, the pieces being of fantastic 

 shapes with a crinkly surface. They arc dark red or black, in colour, and 

 consist of concretionary and stringy ferruginous matter, more or less closely 

 sprinkled with sand-grains. The several pieces often interosculate into a 

 vacuous spongy mass, in which case the rock so closely resembles some of the 

 higher members of the Jurassic series as to be undistinguishable in hand- 

 specimens. In certain well-defined spots the surface of the ground is cover- 

 ed with small,irregularly-shaped, and obviously detrital agates , sometimes white 

 and sometimes tinged yellow and red. These ferruginous beds are frequent- 

 ly seen to overlie well-stratified, soft, white sandstones and earthy beds, which 

 are tinged with pink and purple by the infiltration from the laterite, as seen 

 by the stalactitic form of the coloured parts (see fig. 1, p. 69 of Mr, Wynne's 

 memoir). 



Deposits of this kind are mostly found at levels relatively low as com- 

 pared with the surrounding Jurassics, and they seem to be limited to a level 



