JOHN WESLEY POWELL I33 



This Bulletin also forms the first part of Smithsonian Mis- 

 cellaneous Collections, vol. 20. 



1875. 



7. The canons of the Colorado. By Major J. W. Powell. 



In Scribner's Monthly, an Illustrated Magazine for the 

 People (conducted by J. G. Holland), for January, Febru- 

 ary and March, 1S75, vol. 9, pp. 293-310, 394-409, 523-537, 

 New York, [1S75], 8°. 



8. Physical features of the Colorado Valley. By Major J. 



W. Powell. 



In Popular Science Monthly for August and September, 

 1875, vol. 7, pp. 385-399, 531-542, New York, 1875, S°. 



Introduces the term base-level of erosion. 



9. An overland trip to the Grand Canon. By Major J. W. 



Powell. 



In Scribner's Monthly, an Illustrated Magazine for the 

 People (conducted by J. G. Holland), for October, 1875, 

 vol. 10, pp. 659-678, New York, [1875], 8°. 



10. The ancient province of Tusayan. By Major J. W. Powell. 



In Scribner's Monthly, an Illustrated Magazine for the 

 People (conducted by J. G. Holland), for December, 1875, 

 vol. II, pp. 193-213, New York, [1876], 8°. 



11. Explorations of the Colorado River of the West and its 



tributaries. Explored in 1869, 1870, 187 1, and 1872, 

 under the direction of the Secretary of the Smithsonian 

 Institution. 



Washington: Government Printing Office. 1875. 



291 pp., 4", map and profile diagram in pocket. 



Part first. History of the explorations of the canons of the 

 Colorado. — Part second. On the physical features of the 

 valley of the Colorado. — Part third. Zoology (by Coues and 

 Goode). 



Classification of valleys, pp. 160, 163; base-level of ero- 

 sion, p. 203. 



For revised and enlarged edition see No. 41. 



1876. 



12. Department of the Interior. U. S. Geological and Geo- 



graphical Survey of the Territories. Second division. — 



