237 



Xote. For a portion of the data used iu the preparation of the contour 

 maps, the author begs to aclvnowledge tlie assistance of ^Ir. E. R. Cum- 

 ings and Mr. J. W. Beede, Instructors, Department of Geology, Indiana 

 University, and Mr. J. W. Frazier, student, Indiana University. 



Wabash River Terraces in Tippecanoe County, Indiana. 

 William A. McBeth. 



General Desci'i ption .—The Wabash Valley, in Tippecanoe County, Indi- 

 ana, embraces an area of about eighty square miles. Its average width 

 is about three miles. It is much Avider below LaFayette than above, and 

 it is less wide at that place than elsewhere within the county below the 

 mouth of Tippecanoe River. The width of this valley above the city 

 averages at least two miles, while Itelow it is not less than four. 



The valley comprises a broad, shallow trench, cut by a deeper and nar- 

 rower trench, into the bottom of which is carved the river channel. 



The general surface is about seven hundred feet above sea-level, and 

 the Ijottom of the river channel is about two hundred feet below this. 

 The inner valley or flood-plain tract averages about one mile in width 

 and along this rise the terrace fronts from one hundred to one hundred and 

 fifty feet above the stream. The inner valley is quite uniform in width 

 throughout the county, but the terrace areas are much more conspicuous 

 below LaFayette than above. 



The outer valley is quite straight compared with the inner valley, which 

 meanders from side to side, while the river crossing from side to side of 

 this flood-plain meanders most. 



The Terraces.— The terraces begin a few miles below Delphi, on the 

 west side of the river, an island in the Deer Creek Prairie flood-plain com- 

 prising the farthest up-stream area so far observed. 



The point between the Tippecanoe and the Wabash, where it rises 

 above the flood-plain near the junction, is of this formation. Below the 

 mouth of the Tippecanoe the terraces become conspicuous. On the west 

 side of the stream the region called Pretty Prairie descends gently from 

 the Grand Prairie and terminates in a bluff front which runs parallel with 

 the AVabash at an average distance of a mile from it. 



