THE 



AMERICANJOURNALOFSCIENCE 



[FOURTH SERIES.] 



Art XUI-A Reconnaissance of a Pardon of the Little 

 Colorado Valley, Arizona; by Hekbekt E. Greqoby.* 



st^of 01 /)? w!/ e ° l0giC n ° teS / r< ? the in «dental results of a 

 fSr 7 a ir 11 t r resonrces of that portion of the Little 

 Colorado Valley between Coconino Point and Tanner's Crossi"! 



Geography. 



The area under discussion (see fig. 1 ) i s a portion of the 

 Colorado Plateau Province, and presents in i?s topo°mp y 



valley floor of the Little CoTo^ K^n uiles~ g ft 



:rt°tl J I 8 ^ d6flned b 7 the ™* -ndsTone cliff 

 Waid Terracef and Us western border is equally well 

 marked by the bold front of Coconino Point The L Itle 

 Colorado occup es a narrow rock trench 40 feet deep at 

 Government Bridge ; below that point the depth of tKnvon 



XT Cedar «™£ 3 °° *? 4* ^ -thte CoS" 



course from sL^ IP**** Little Colorado after a long 

 tributarv valW /TiT° M °" ntains > but the other western 

 areas o>\ ftl? fla t-.fl°°red narrow canyons with drainage 



areas of a few square miles. An intricately dissected surface 



fren?reH leh 7f bntte8 ?$ meSaS of ^"dimensions ca ved 

 from red sandstones and shales, may be taken as typical for 

 this portion of the Little Colorado Valley 7P 



Ihe annual precipitation in the lower Little Colorado Vallev 

 is probably less than 3 inches, and varies over 100 per cent 

 from season to season. The rain comes as infrequen&Xn 

 showers; and is hurried away to innumerable channels or 



* Published by permission of the Director o£ the U S Geolosical Snrvev 

 t Named m honor of the late Dr. Lester F. Warn ^"'ogica! burvey. 



Am. Jour. Sci.-Fourth Series, Vol. XXXVIII, No. 228.-Dec, 1914. 



