265 



sist of a deep red, pebbleless and structureless loam, the origin of which 

 is an unsolved problem. The red loam, even upon moderate slopes, gullies 

 rapidly and has greatly facilitated the dissection of the region. 



The Wabash Plain, two miles in width, presents the usual flood plain 

 features of levees and bayous. At one point. S. W. $ of S. E. I of sec- 

 tion S, shale outcrops in the midst of the alluvium. Before the valley was 

 filled this was an island in the river with deep water all around it. The 

 valley filling iu some places is 80 feet deep, and consists of sand and gravel 

 carried into the valley by water and floating ice. At a railroad gravel pit 

 in section 36 twenty-five feet of fine gravel is exposed, with an occasional 

 stratum containing enough clay to resist rain wash and cause the forma- 

 tion of earth pillars two or three feet high. A terrace of coarse, roughly 

 stratified gravel formerly occupied an area about one mile by one-half 

 opposite the city of Terre Haute and was an island at high water. The 

 town of West Terre Haute stands upon the southern half of it. The north- 

 ern half has been entirely removed by the railroad companies and exca- 

 vated to the level of low water in the river. The remaining surface is 

 from 15 to 25 feet above the plain. 



The Sugar Creel; Drainage System presents several peculiar features 

 and furnishes some of the most interesting problems of the area. The 

 small tributaries of the Wabash are usually of the parallel type, not com- 

 bining into systems, the main streams flowing nearly at right angles to 

 the Wabash. The Sugar creek system is fan-shaped, consisting of four 

 principal streams which converge southward and eastward to a junction 

 and pass out through a single gap upon the Wabash plain. East Little 

 Sugar creek flows southward seven miles parallel with the Wabash river 

 and about one mile west of the bluff. In sections 25 and 20 a nameless 

 stream flows about one mile eastward, turns northward one-half mile and 

 again eastward, both bends being right angles. This seems to be due to 

 harder material in the stream's course. 



Sugar Creek Lake. — At the western border of the area surveyed the 

 valley of Sugar creek widens abruptly from less than one-half mile to about 

 a mile. Two miles below it narrows abruptly and flows for a mile through 

 a gorge twenty to forty rods wide. The expansion and the narrows pre- 

 sent each its own but related problem. 



The expanded portion of the valley, about one mile by two, is bounded 

 on the south by a boulder clay bluff sixty feet high: on the north bv lower 



