SAWYER CLIMATIC CHANGE IN ILLINOIS. 257 



main stream passes through heavy timber for about three miles, 

 the rest of the distance is prairie, with the usual amount of wil- 

 lows. The original bed of the creek averaged 7 feet . wide and 

 2 J feet deep, but in time of high water it would average 100 feet in 

 width : below the falls it is now 21 feet wide and 9 feet deep, and 

 never overflows its banks ; the increased width is therefore 14 ft., 

 and the depth 6 J feet. These foils have travelled over 3,650 yards 

 since 1849, leaving an impassable barrier behind them. It has 

 displaced about 35,680 cubic yards of alluvial soil and clay, 500 

 cubic yards of gray "hard-pan," and 320 cubic yards of pipe-clay. 

 The above shows an annual average progression of 146 yards, 

 and an annual displacement of 1460 cubic yards, or about 1700 

 tons. From 1849 to 1853, or 4 years, it travelled 1650 yards, an 

 average of 412^ yards per year. It required 2 years to work its 

 way through =^0 yards of "gray hard-pan" ; but like an army long 

 kept at bay, yet finally overcoming the obstacle which for a time 

 prevented its further progress, it rushed on with irresistible im- 

 petuosity, and, after causing the downfall of many a mighty mon- 

 arch of the forest, we find our little Niagara in 1859, °^ ^" 4 years, 

 1500 yards further up stream, showing an advance of 375 yards 

 per year ; nearly a fourth of this time, however, was spent in 

 passing 32 yards of pipe-clay. It now passed two of its tributa- 

 ries, thereby reducing the amount of water nearly one-half; con- 

 sequently its progress has been less rapid, although the depth 

 remains the same. From 1859 to 1873 it has been working its 

 way through ordinary hard-pan, 450 yards ; since January, 1874, 

 it has cut out 50 yards more, the season being very favorable for 

 the work. It now has about 3,000 yards to traverse through the 

 prairie ere it completes its work ; yet the task will be compara- 

 tively easy, and without a doubt will be accomplished during the 

 next 25 years. 



Every little streamlet is bringing its bed down to a level with 

 its parent stream, and the merry rippling of their little cascades 

 greets the ear on every side, and tells you in language not to be 

 misunderstood that they will in time accomplish the work allot- 

 ted them to perform — the thorough drainage of the land through 

 which they pass : and, when this shall have been accomplished, 

 that it will necessitate some system of irrigation in order .to suc- 

 cessfully cultivate the soil, I think there can be no doubt ; in fact, 



iii— 17 [Mar. 25, 1875.] 



