312 Capt. Grant on the Geology of Cutch. 



even anticlinal lines. The basalt is very hard, compact, and of a dark blue 

 colour, and presents irregular masses, without the slightest approach to a co- 

 lumnar structure. 



Distinct Periods of Volcanic Eruption. — That the volcanic eruptions have 

 occurred at many distinct periods, is also evident, from the different formations 

 with which the igneous rocks are associated, and from the variations in their 

 characters. Thus, in the same section, the lower part frequently consists of 

 large, rolled, or water-worn masses, whilst the upper portion is columnar : in 

 other places the basalt alternates with a calcareous grit or coarse limestone, 

 having a tabular structure, but always distinctly stratified, and very brittle, so 

 as to present perpendicular banks. This limestone is generally associated 

 with basalt, where the latter is raised into hills; and from the fdct of angular 

 pieces of basalt or igneous matter being imbedded in it, would incline one 

 to believe that, in such cases, it must be contemporaneous, though it often 

 regularly alternates with it. In other places the basalt is interstratified with 

 a pure crystalline limestone or travertin. 



The principal mass of igneous rocks (see Map) lies towards the southern 

 department of the province, and forms a group of hills called the Doura range ; 

 the intervening spaces and the ground at their southern base generally 

 assuming a porphyritic structure. The northern parts of the range have, for 

 the greater part, a flat, smooth outline ; but in the interior of the group are 

 many clusters of small, conical hills, arranged round a circular space, inclosing 

 a kind of hollow. The sides of these cones are very steep, and invariably 

 present innumerable horizontal lines, forming rings resembling narrow paths. 

 The surface being covered with basalt, in very small pieces, is totally devoid 

 of vegetation, and has precisely the appearance of a newly-laid macadamised 

 road. Their interior, however, has a much more solid construction, as is well 

 seen in numerous deep clefts and ravines with which the hills are in all direc- 

 tions intersected. 



One of these ravines, near the village of Doonee, is 50 or 60 yards broad, 

 and nearly 100 feet deep ; and its perpendicular sides are composed of com- 

 pact columnar basalt of a greenish grey colour; the columns being perfect 

 polygons, and of a very large size. This rent must have been formed by 

 some convulsion, as it reaches nearly to the summit of the hill ; and the only 

 water that could ever have flowed down it being that which falls on its sides 

 and bed, and must be very little. 



Alternations of Basalt with Strata of the Upper Secondarij Formation. — Near Nurra, on the 

 borders of the Runn, a hill called Joge-ki-bit, basalt alternates with slate-clay, limestone slate, 

 slaty limestone, and a laminated loam. The strata dip from 40° to .50° to the north, which being 



