ORIGIN OF ROCK-SALT. 21 
question. All I conceive to be required, is to imagine the river, 
for a time, ceasing to flow into the lake, or its waters diverted. 
Its volume had evidently been diminishing, or the salt-rock 
could not have accumulated. Fancy then, and there is nothing 
extravagant in the idea, the river silted up, and the waters 
turned aside. A summer or two would suffice to turn the mass 
of briny water into a hard rock, and there we leave it—a per- 
fectly formed bed of rock-salt. So things would remain until 
some rainy season, when floods swept the country, and sent 
their foaming waters along the old course of the river; it is 
not wonderful if it broke down the temporary barrier, and once 
more flooded, with its mud-laden waters, the floor of rock-salt 
in the old lake. 
What would then happen? There was sufficient saline matter 
present to cause the clay to settle and cover the bed of salt. 
This vould continue for a lengh of time, and under similar 
conditions to the first bed; the result would be a considerable 
deposit of marl. In this way we may account for the second set 
of beds, by alternately shutting out and letting in a supply of 
suitable water. The diversion of the supply of water pave rise 
to the salt, the letting in of more water produced the marl. | 
I am conscious that I have but imperfectly fulfilled my object 
in endeavouring to solve some of the many problems connected 
with the formation of rock-salt; and as an humble effort in 
that direction, I now submit it to the consideration of the 
geological student. 
