1840.] 



On the Geology of Cutch, 



339 



Numerous Echmodermaia, and other fossils, are found on the table- 

 land, and some of the fields are thickly st ewed with casts of a Turbinel- 

 la of a very large size, the external shell being always waDting. On 

 breaking them, small fr agments of igneous matter are found in their in- 

 terior. 



In the table-land just south of the outburst, is a large fissure, about a 

 quarter of a mile in length, 40 yards broad, and 40 or 50 feet deep. One 

 extremity communicates with the river, and the other is rounded, or 

 formed into a basin shape. The sides are perfectly perpendicular ; and 

 it is clearly an opening in the ground, there not being the slightest indi- 

 cation of anything of the kind, until directly at its brink. I was inform- 

 ed by a native of the village, (the only present inhabitant,) that smoke 

 issued from the outburst about twenty-two years since ; but little de- 

 pendence can be placed on the statements of these people. 



Another similar, but smaller, outburst occurs about three miles south 

 of Mhurr, near the spot in which, in my account of the tertiary deposits, 

 I mentioned that a large basaltic dyke crosses the river. The space 

 here blown out, does not exceed 100 yards in diameter, and 15 feet deep, 

 consisting of similar cones of volcanic scoriae, and comminuted particles, 

 as above described ; but there is no trace of any basalt nearer than the 

 dyke in the river. 



From what I have now detailed, it appears, that igneous action has 

 affected all the formations of which the province is composed ; and it 

 will also appear, by the following details, that the Grand Runn, the 

 most remarkable feature of the country, owes its peculiar characters to 

 volcanic action. 



The Grand Runn. 



With a short account of this large and singular tract, I shall conclude 

 the paper. It has been described by Captain Burnes, in a memoir in the 

 library of the Royal Asiatic Society; and referred to, at considerable 

 length, by Mr. Lyell, in his " Principles of Geology."* 



This tract, containing an area of upwards of 7000 square miles, ex- 

 clusive of the space occupied by the Bunnee, and the islands of Puchum, 

 Khureer, &c., is, perhaps, unparalleled in any known part of the globe, 

 as it may be said to be placed on a level between land and water. It is 

 ' dry during the greater part of the year, when its surface consists of a 

 sandy flat, totally devoid of vegetation ; but, perhaps, on account of its 



♦ 5th Edit., vol. ii, p. 183 et seq. 



