1840.] 



On the Geology of Cutch. 



331 



half a mile of the hill, the ground near it being strewed with small frag- 

 ments of igneous rock. 



The cause of the elevatiDn of this hill is, in my opinion, distinctly visi« 

 ble in the banks of a river which passes by its western base. They are 

 from 20 to 30 feet in height, and are composed of white calcareous marl, 

 covered by a thin bed of gravel. Immediately opposite the hill, these 

 beds are cut through by a dyke of very compact dark green basalt, form- 

 ing, towards the river, a wall about eight feet high ; its base being hid 

 by a talus of gravel. In several places on each side of this dyke, which 

 is about 50 yards in breadth, independent masses of igneous rock break 

 through the marl. They are principally of a blunt, conical form, capped 

 with portions of the marl, and consist of spheroids of basalt, which des- 

 quamate in concentric layers, precisely resembling scales of iron. At a 

 short distance up the river, or northward, this marl is covered by a stratifi- 

 ed series, dipping at a high angle to the north, and consisting of a yellowish 

 marl, with small imbedded fragments of lignite, covered by a bed of blue 

 clay, containing also fragments of lignite and quantities of an olive-brown 

 earth, in which small pieces of either amber or mineral resin are inclosed. 

 Above this bed is a stratum of red sandstone ; and the whole is covered, 

 at its lower extremity, by a thick bed of gravel. These inclined beds 

 reach the level of the water about 400 yards from the basaltic dyke, be- 

 yond which the marl again appears in horizontal beds. Southward of 

 the dyke, the change from the broken part to the undisturbed horizon- 

 tal strata, is much more abrupt, occurring within a very short distance. 

 On the top of the bank adjoining the south end of the dyke the stratified 

 beds of blue clay, &c. are horizontal. 



From the above description it appears, that the only place in which 

 the basalt is exposed, is directly under the hill, no trace of it being dis- 

 cernible either above or below this spot ; also, that the most compact and 

 extensive mass of basalt is exactly under the highest part of the hill ; 

 and that detached masses of igneous rock present themselves, with 

 large portions of the marl adhering to them. A series of stratified beds 

 is also noticed rising from the north towards the hill, meeting the sur- 

 face at its foot, and is again found in a horizontal position just south of 

 the hill. All these facts surely prove, that the hill must have been ele- 

 vated by an outburst of igneous matter, which was probably a branch 

 from the basaltic hills to the eastward ; one of its forks reaching within 

 half a mile of the spot. 



Quantities, of what I believe to be frothy or foam lava, being a brown • 

 ish black substance, very vesicular or spongiform, extremely light, and 



