108 



bulletin: museum of comparative zoology. 



FAOB 



Stage of Development of the 

 Canyon 168 



Rapids in the Canyon . . . 168 



Junction of Trunk and Branch 



Streams 169 



The Geological Section in the 



Canyon Wall 171 



The Two Unconformities . . 173 

 Correlation of Water Streams 



and Waste Streams . . . 176 



Cirques, Cusps, and Niches . 178 

 The Esplanade 180 



Two Theories of the Esplanade 181 



Comparison of the Kaibab and 

 the Kanab Sections . . . 181 



Eastward Fading of the Es- 

 planade 182 



Relation of the Inner and Outer 

 Canyons 183 



PAGE 



Relation of the Esplanade to 



the Toroweap Fault . . . 184 

 Conclusion as to the Origin of 



the Esplanade 185 



Hints for a Visit to the Canyon . 18(5 

 Former Climates of the Grand Can- 

 yon District 187 



Diverse Opinions of Early Ob- 

 servers 187 



Moist Miocene and Arid Plio- 

 cene Climates 188 



The Toroweap 189 



The Pluvial Equivalent of the 



Glacial Period 192 



Volcanic Phenomena 192 



Summary 195 



Bibliography 197 



Explanation of Plates 201 



Introduction. 



In June, 1900, it became possible for me to visit the district of the 

 Grand Canyon of the Colorado, and to see upon the ground the wonder- 

 ful features of a region that had long been familiar from the reports 

 of our governmental surveys. Our party consisted of Prof. R. E. 

 Dodge of Teachers' College, Columbia University, Prof. H. E. Gregory of 

 Yale University, Mr. R. L. Barrett of Chicago, Mr. Richard Wetherill 

 of Pueblo Bonito, N. M., Dr. Tempest Anderson of York, England, and 

 the writer. We reached Flagstaff, Arizona, by the Santa Fe Western 

 Railroad on June 3, spent twenty-three days travelling irregularly across 

 country, and went out from Milford, Utah, to Salt Lake City by a 

 branch of the Oregon Short Line on June 26. Our itinerary is shown 

 on the accompanying outline map, Figure 1, with dates of camps, and 

 in the list of camps given below. We travelled partly in wagon, partly 

 on horseback, and averaged about twenty-five miles a day. The clouds 

 of thunder showers were frequently seen in the distance, but we had 

 rain only twice ; first a few drops in the canyon, June 7, and next a 

 brisk shower near the Little Colorado crossing on the morning of June 

 10; the centre of this shower passed north of us, and the muddy 

 streams from its short-lived down-pour met us as we were ascending 

 a dry arroyo, or " wady." Many days were almost cloudless and 

 oppressively hot over noon. The nights were cool, with the exception 



