334 



On the Geology of Cutch, 



[Oct. 



occupying from 200 to 300 square yards, and being about eight feet in 

 height, remain every here and there, similar to a field of corn partially 

 reaped. The columns are very regular, generally four- sided, with 

 smooth, even surfaces, and are composed of a hard, compact, dark blue 

 basalt. 



Another instance of the junction of the limestone grit with the basalt 

 is near the village of Choolree, a little to the westward of Kaira. The 

 basaltic range is completely divided by a narrow ravine, in which the 

 two rocks appear in contact, the limestone being broken in all direc- 

 tions. One side of the ravine presents a perpendicular cliff, of nearly 

 80 feet in height, of irregular columnar basalt, overlying a bed of round- 

 ed masses of the same, t'.iough the opposite bank is composed of the 

 limestone grit. Advancing through the Pass, the basalt terminates ab- 

 ruptly, and is succeeded by the limestone grit, which forms both sides of 

 the ravine. Further on, the basalt again appears in the form of a dyke ; 

 beyond which is the grit, once more succeeded by a dyke of basalt, form- 

 ing, at this extremity of the Pass, both banks. Where the dykes of basalt 

 occur the limestone lies in immeni>e masses, evidently broken off at the 

 time of the projection of the upper bed of igneous rock ; being itself 

 of subsequent formation to the lower basaltic bed of rolled masses. 

 This is very distinctly shown at one part of the Pass ; and it should be 



mentioned, that the bed of the ravine consists throughout of irregular or 



broken basalt. 



The intervening spaces and the ground at the base of these hills 

 are composed, for the most part, of a red clay much resembling brick* 

 a variety of it being amygdaloidal, of a darker colour, extremely hard 

 and tough, and containing quantities of calcareous spar, chalcedony, rock 

 crystal, &c. 



In some places it forms low ranges of hills of a hard rock, of a dingy 

 red colour, thickly interspersed with cylindrical kernels of zeolite, with 

 a light green coating, some of them dividing into two parts. Other 

 specimens contain numerous crystals of felspar ; and, in many in- 

 stances, all the mineral substances have disappeared, leaving a vesicular 

 mass. Occasionally, thin beds or layers of calcareous spar, of a leek- 

 green colour, are met with, also of rock crystal and chalcedony in all 

 its varieties. The surface of the plains is covered with fragments of 

 these minerals, derived from the disintegration of the amygdaloids, which 

 are rapidly affected by exposure to air and water. Some of the sides of 

 the hills are covered with heaps of rock crystal, as if cart-loads had been 

 purposely thrown down. 



