246 
THE COPPER MINES TO 
Again we pushed on, having yet about fifteen 
miles between us and the first place where there was a 
certainty of finding water. Continuing a few miles 
through this defile, which presented no difficulty for 
our wagons, we emerged on the opposite plain, where 
our eyes were greeted with the sight of a long white 
streak, which we would have taken for a lake, had it 
not been designated by Colonel Cooke, as Las Playas^ 
or the dry bed of a lake. Keeping on the same south- 
easterly course, we still descended ; and as the road 
was very smooth, we set the mules on a trot and rolled 
over it at a pretty good pace, considering the long 
distance we had come. At three o’clock we struck 
the playas, which seemed to have an extent of twenty- 
five or thirty miles from the north-west to the south- 
east, the general course of the mountain ranges and 
valleys in this region. The surface of this dry bed 
was an indurated clay, so hard that the wheels of our 
wagons scarcely made an impression. Its color was 
nearly white. After rains, this basin, being surrounded 
by high mountains, receives a large amount of water, 
which seems to evaporate before vegetation gets a 
foothold. From indications along its margin, and 
from what I afterwards saw in other places, it never 
could have contained more than two or three inches of 
water in its deepest place. The width, where we 
crossed, was about a mile and a half As we were 
midway across, a beautiful mirage suddenly presented 
itself towards the south, which led us to believe that 
the further end of the dry surface we were rolling 
over, was in reality a body of water. Little clumps of 
bushes arose from it like islands ; and the very grass 
