May, 1908.] Stream Diversion near Lakeville, Ohio. 349 



LITERATURE. 



1. Adams, C. C. Southeastern U. S. as a center of geograph- 

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 3:115-131. 



2. Dachnowski, A. Zur Kenntnis der Entwicklungs-Physio- 

 logie von Marchantia polymorpha. Jahrb. f. wiss. Botanik 

 1907, XLIV: 254-286. 



3. , Ravines in the vicinity of Ann Arbor. 



Michigan Academy of Science, Report 9:113-122. 1905. pl22. 



4. Davenport, C. B. Statistical methods with special refer- 

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 1899; and Revised edition 1904. 



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6. Pearson, K. Grammar of Science. 1900. 



7. , On the sources of apparent polymorphism 



in plants, etc. Biometrika 1902; 1:304-306. 



8. Shull, G. H. Place constants for Aster prenanthoides. 

 Bot. Gaz. 1904; 38:333-375. 



9. Transeau, E. N. Climatic Centers and Centers of Plant 

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STREAM DIVERSION NEAR LAKEVILLE, OHIO.* 



George D. Hubbard. 



The announcements of stream modifications have come to us 

 so often in the last generation that we no longer wonder at them. 

 They are very common and most of the larger streams have 

 been subject to one or more of them. With all the examples 

 which have been described and explained there has come a 

 great variety of form and cause, yet a classification under three 

 heads is possible. Some are simply diversions in which the 

 stream had nothing to do but to get out of the way ; these occur 

 most frequently in glaciated regions. Other causes are land and 

 snow slides, lava flows, volcanic eruptions and artificial obstruc- 

 tions. Some are adjustments in which the stream modifies its 

 course or the form of its valley because the one or the other is 

 out of harmony or adjustment with the needs of the stream; 

 these occur in regions where superposition or rejuvenation 

 have occurred and the stream in its later stages is in different 

 rocks from those in which it worked in youth. The third class 



*Presented to the Biological Club, February 3, 1908. 



