CONTENTS. 



PAGE. 



Introduction i 



Laboratory location trip 2 



Itinerary . , 2 



Arid region of western Texas 3 



Sand dunes of Cliihuahua 4 



Tularosa desert . 5 



Analyses of sands 8 



Tucson as a laboratory site 12 



History 14 



Nogales . . . 17 



Torres 17 



Guaymas ,19 



Colorado desert 20 



Mohave desert 22 



Grand Canyon of the Colorado 23 



Plant life in North American deserts 23 



Meteorology . i$ 



Tables 25 



Discussion 27 



Soil 29 



Historical 32 



Transpiration and temperatures 38 



Bibliography 46 



