34:4 RUJSTN OF CUTCri. [Ch. xxu 



nislied to me by the late Sir Alexander Barnes, of that singular flat 

 region called the Rimn of Ciitch, near the delta of the Indus, which is 

 7000 square miles in area, or equal in extent to about one-fourth of Ire- 

 land. It is neither land nor sea, but is dry during a part of every year, 

 and again covered by salt water during the monsoons. Some parts ol 

 it are liable, after long intervals, to be overflowed by river-water. Its 

 surface supports no grass, but is incrusted over, here and there, by a 

 layer of salt, about an inch in depth, caused by the evaporation of sea- 

 water. Certain tracts have been converted into dry land by upheaval 

 during earthquakes since the commencement of the present century, and, 

 in other directions, the boundaries of the Runn have been enlarged b\' 

 subsidence. That successive layers of salt might be thrown down, ono 

 upon the other, over thousands of square miles, in such a region, is un- 

 deniable. The supply of brine from the ocean would be as inexhausti- 

 ble as the supply of heat from the sun to cause evaporai'on. The only 

 assumption required to enable us to explain a great thickness of salt in 

 such an area is, the continuance, for an indefinite period, of a subsiding 

 movement, the country preserving all the time a general approach to 

 horizontahty. Pure salt could only be formed in the central parts ol 

 basius, where no sand could be drifted by the wind, or sediment be 

 brought by currents. Should the sinking of the ground be accelerated, 

 so as to let in the sea freely, and deepen the water, a temporary suspen- 

 sion of the precipitation of salt would be the only result. On the other 

 hand, if the area should dry up, ripple-marked sands and the footprints 

 of animals might be formed, where salt had previously accumulated. 

 According to this view the thickness of the salt, as Avellas of the accom- 

 panying beds of mud and sand, becomes a mere question of time, or 

 requires simply a repetition of similar operations. 



Mr. Hugh Miller, in an able discussion of this question, refers to Dr. 

 Frederick Parrot's account, in his journey to Ararat (1836), of the salt 

 lakes of Asia. In several of these lakes west of the river Manech, " the 

 water, during the hottest season of the year, is covered on its surface 

 with a crust of salt nearly an inch thick, which is collected with shovels 

 into boats. The crystallization of the salt is effected by rapid evapora- 

 tion from the sun's heat and the supersaturation of the water with mu- 

 riate of soda ; the lake being so shallow that the little boats trail on the 

 bottom and lea'\ e a furrow behind them, so that the lake must be re- 

 garded as a wide pan of enormous superficial extent, in which the brine 

 can easily reach the degree of concentration required." 



Another traveller, Major Harris, in his " Highlands of Ethiopia," de- 

 scribes a salt lake, called the Bahr Assal, near the Abyssinian frontier, 

 which once formed the prolongation of the Gulf of Tadjara, but was 

 afterwards cut oft' from the gulf by a broad bar of lava or of land up- 

 raised by an earthquake. " Fed by no rivers, and exposed in a burning 

 climate to the unmitigated rays of the sun, it has shrunk into an ellipti- 

 cal basin, seven miles in its transverse axis, half filled with smooth water, 

 of the deepest cerulean hue, and half with a solid sheet of glittering 



