266 On the Strata of the Dtidb Alluvium, [May, 



The total absence too of iron within the bounds I am endeavouring 1 to 

 treat of, in any of the alluvial formations, and the intimate connexion 

 existing between the sandstone, and substances of undoubted volcanic 

 origin, strongly incline me to the opinion, that the heat necessary for 

 the production of the latter, might have split the former, and that the 

 interstices thus produced, have filled with the lava, (the present veins,) 

 in a state of fusion. Another circumstance, confirmatory of this, is 

 the fact of the sandstone being in a state of transition with the vitri- 

 fied substances ; but owing to the brittleness of the intermediate sub- 

 stance, (spec, d.) it was with the greatest difficulty I could procure 

 the accompanying specimens. 



Of the Volcanic Rocks. 

 These occur in two separate situations, namely, at Murka and Mhow. 

 You will perceive, Sir, that the specimens from the former place, agree 

 with Nos. 4, from the latter, although the shortest distance between 

 these places cannot be less than 20 miles, perhaps more. 



The mass at Murka, consisting of rough spheroidal blocks, varying 

 from one by two, to three by five feet, lies on the right bank of the 

 river ; their peculiar shape, appearance, and position, leads me to 

 imagine, that they have been ejected in a partially vitrified state, and 

 lodging in the water, the outer and angular parts have become slack- 

 ed, and have been swept away by the stream, leaving these blocks, 

 which, under these circumstances, are exactly similar to the core of 

 badly burnt lime ; in no other way can I account for their peculiar 

 formation, which had it been produced by rolling, the same cause 

 would have scattered them widely, but this has not been the case, as 

 they lie in a clearly defined mass, (fig. 2. PI. XV.) and in this instance, 

 have no other connexion with any other stratum than being super- 

 incumbent. 



They correspond exactly with Nos. 4, from Mhow, both in the de- 

 gree of vitrification, colour, texture, and every thing but position ; 

 those at Mhow overlie, but are entirely detached from their bed, 

 (sandstone,) and the same quantity is scattered over a greater space 

 than at Murka. Their exterior is jet black, and so highly polished, 

 that it is impossible to examine them for any length of time when the 

 sun shines, the great light and heat they reflect during the day is pe- 

 culiarly distressing to the vision. The interior is a mottled dark, and 

 light red, one view of which is conclusive of its volcanic origin. 

 (Specs. 3 and 4.) 



Nos. 5, are specimens also from Mhow, the originals, (spec. 5,) 

 occur in very considerable masses, having both sandstone and clay as 

 a base, and standing above it from 1 to 20 feet ; the largest of these 



