59 



dry on the surface, cracked in lines like a coarse, irregular 

 net, and here and there shining white with crystals of alkaline 

 salts. Over vast stretches, the salt formed a brittle, glistening 

 crust, which collapsed rottenly under the horses' feet, letting 

 them through into gluey mire. Most of the time we went 

 afoot, driving our tired animals ahead. The heat was in- 

 sufferable. One of the burros gave out, so that we had to 

 distribute her pack among the others, already over-burdened. 

 We had endless trouble in keeping them on the right way 

 over the fifteen miles of trackless desert. 



In the midst of this terrific heat, the mirage was tantalizingly 

 perfect. All around us, at a distance of perhaps half a mile, 

 seemed cool, blue lakes, gleaming in the sun, stretching away 

 to the foot of the mountains and to the willow-fringed Hardy. 

 Off the northern end of the Pintos, were small dark buttes 

 and clumps of mesquite trees which seemed rocks and islets 

 extending from a promontory into an ocean. Southward, 

 beyond all this vast sea of thirst, rose the bluish heights of 

 La Providencia, the mightiest picacho of the sierra of San 

 Pedro Martir (10,000 ft.), its crest marked with gullies full 

 of snow.^ In this day's heat it was almost impossible to 

 believe that less than three months before several cattlemen 

 had been frozen to death near the base of that mountain. 



Over all this expanse of baked mud we saw no suggestions 

 of life save reddish desert flies (Tahanus), dead snails,^ and a 

 few bird bones, but when we drew near the sand dunes and 

 brush patches of the far side, a lean coyote sneaked out ahead 

 and showed us his heels. When we reached the higher ground, 

 towards the Tinaja^ foothills, we found the ground strewn 



1 For a fascinating description of this wonderful, uncharted sierra, see 

 the paper by A. W. North (1907). 



2 Planorhis lumens Carpenter, a discoidal, air-breathing, fresh-water 

 Limnseid, and Ceriihidea sacrata Gould, a spiral, brackish-water, amphibious 

 mollusk. It is interesting to find the latter, an estuarine shell, together 

 with a typical fluviatile species. Whether the Ceriihidea thrives in the 

 Colorado delta through the beneficent effect of tidal bores, or whether it 

 has become widely distributed around the salty inland sinks, I do not know. 



3 A tinaja is an earthen water-jar, and these mountains are so called 

 because of the presence of pot-holes which serve as natural reservoirs for 

 rain-water. 



