86 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
alone is shown by the relation of the terraces formed during successive 
stages of down-cutting. Great opportunity has thus been given for 
the development of adjusted drainage. Fine examples of master con- 
sequent, subsequent, and beheaded consequent streams are shown, 
while less perfectly developed specimens of obsequent and resequent 
streams are also to be found. The general immaturity of all the 
streams described indicates that the uplift which permitted their 
development was relatively recent and may even be still in progress. 
BIBLIOGRAPHY. 
Crosby, W. O. 
Geology of the Black Hills of Dakota. Proc. Bost. Soc. Nat. Hist., 1888, 
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Darton, N. H. 
a. Preliminary description of the geology and water resources of the 
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b. Comparison of the stratigraphy of the Black Hills, Bighorn Moun- 
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Davis, W. M. 
a. The development of certain English rivers. Geogr. Journ., 1895, 
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Eldridge, G. H. 
A geological reconnoissance in northwest Wyoming. U.S. G. S., Bull. 
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Emmons, S. F. 
See Irving, J. D., Emmons, $. F., and Jaggar, T. A., Jr. 
Gilbert, G. K. 
Lake Bonneville. U. S. G. S., Monograph 1, 1890. 
