490 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



or esker troug-h which continues to the moraine at Huntsville, but the ridge 

 itself falls short a mile or so of reaching the moraine. The esker has a 

 width of 30 to 75 yards, including slopes, and a height in its northern half 

 of 15 to 25 feet, but in its southern half its height seldom exceeds 10 feet. 

 The trough in which the esker lies has an average width of 150 to 200 

 yards and is excavated only a few feet below the bordering plain, so that 

 the higher parts of the esker rise above the level of the plain. The esker 

 winds greatly, but the trough in which it lies has a trend nearly in line 

 with the striae of a neighboring quarry (S. 25° W.). In the northern half 

 of its course the esker exhibits the great changes in direction indicated by 

 the bearings given below, which are taken in order from north to south by 

 a pocket compass: S. 5° W., S. 50'= W., S. 35° W., S. 30° E., S. 10° W., 

 S. 25° E., N. to S. The portion bearing S. 30° E. is but a few rods in 

 length. The portion bearing S. 25° E. is somewhat longer, but the greater 

 part of the esker bears west of south. The southern half of the esker con- 

 sists of short ridges which form a chain trending northeast to southwest, 

 but the gaps in the chain are very narrow. The esker appears to be com- 

 posed of assorted material throughout its entire length. There is a railway 

 gravel pit near its south end which exposes sand at the base of the ridge 

 and gravel in its upper two-thirds. The beds present considerable arching 

 and oblique arrangement. It is scarcely probable, however, that this one 

 exposure can be taken as an index of the character of the beds in the 

 whole ridge, iov where eskers have been more extensively opened obsei'va- 

 tion has shown hem to vary greatly in structure within short distances. 

 The phenomena this esker and its trough, like those of eskers and esker 

 troughs in general, lead to the conclusion that it was deposited by a stream 

 flowing under the ice, that the stream had previously eroded the trough in 

 which the ridge lies and had its discharge at the ice margin. The produc- 

 tion of such a trough, and more especially of such a ridge, appears to 

 demand a nearly stagnant condition of the ice sheet, or an exact balancing 

 of movement and erosion, such as would prevent a filling of the trough and 

 an obliteration of the ridge. 



THE MUNCIE ESKER. 



A brief description of the Muncie esker appears m each of Dr. Phinney's 

 reports on Delaware and Henry counties, Ind.,^ and through his kindness 



1 Eleventh Ann. Rept. Geol. Survey Indiana, 1881, p. 134; Fifteenth Ann. Kept. Geol. Survey 

 Indiana, 1885-1886, p. 108. 



