1840.] of the Great Basaltic District of India. S7 



considered by every observer to form the eastern part of the great basal- 

 tic formation of Western India, with which it is continuous, and with 

 which it agrees in every particular of general character and mineralogical 

 structure, and in being connected with stratified rocks, which, as far as 

 is yet known, are of the same age. The only difference is, that towards 

 the eastern limits of the formation, the hills are less elevated and the trap 

 bre;iks through the granite and stratified rocks, while to the west the 

 mountains are, with a few exceptions, entirely composed of basalt from 

 the level of the sea to the loftiest summits. 



Zonar Lake, Sfc. — The Sichel hills, which have heretofore attracted 

 little attention in a geological point of view, terminate to the west in the 

 neighbourhood of Lonar, near what appears to have been a vast crater in 

 the cenire of the great basaltic district. As it is the only instance of a 

 volcanic outburst discovered in this immense Plutonic region, a more de- 

 tailed account of it than has yet been given to the public, may not be 

 unacceptable*. 



It is a nearly circular or oval depression, in a country composed of ta- 

 bular and nodular basalt, and sloping gently towards it on every side. 

 It is between three and four miles in circumference at the upper margin 

 of the precipitous escarpment which rises from the bottom of the valley 

 about 500 feet. The extent from which the water is collected may be 

 about six miles in circumference, but no measurements were made. Two 

 small streams fall into it from above ; one issuing from a pagoda, to which 

 it is carried from the gentle slope behind ; and the other passes over a small 

 cliff, (PI. B.) on which it deposits a considerable quantity of stalactite. The 

 sides of the crater are covered with a forest inhabited by tigers and game ; 

 and the bottom is occupied by underwood, a few fields, in the irrigation 

 of which the water of the streams is neirly expended, and by a small 

 lake of salt and bitter, greenish water, surrounded by a muddy shore, and 

 varying in size at different seasons. Many sweet springs issue from the 

 saline mud, and a well is built within its highest level, the water of which 

 stands at the same height as that of the lake, though issuing from a depth 

 of nearly twenty-four feet. 



I have carefully examined the water of this well, and that of the small 

 stream at the pagoda above. This last had a specific gravity of 1000-6 ; 



* Captain Alexander has pul)lished a notice of this lake in the Transactions of the Lite- 

 rary Society of Madras, and in the Edinburgh Philnsoohical Journal ; hut he must have 

 examined it very cursorily or he would not have overlooked its real nature, and stated it 

 to be unfathomablp, when, in fact, the water is everywhere shallow. An extract from a 

 private letter to Mr. Prinsep, and piiblished in his Journal for June 1834, was written 

 before I had myself examined the chemical history of the lake. 



