32 BIG SPRING PRAIRIE. 



most of the earlier ditches were dug chiefly along the 

 edges of prairie, thus intercepting the waters irom the 

 springs. The destruction of the forests on the ridges, 

 and the construction of tile ditches and open ditches 

 have considerably lessened the importance and magni- 

 tude of the springs along the margin of prairie, thus 

 aiding in the evolution of plant societies. After the 

 soil became drier, and especially after the construction 

 of the Hocking Valley R. R. across this area, prairie 

 fires became prevalent. 



In order to investigate the amount and causes of 

 the settling of the soil, direct experiments with soils 

 were performed. Samples of soil were collected, 

 weighed, and measured while still wet. After thorough- 

 ly drying in a slow oven, the soil was again weighed 

 and measured. The dry soil was then burned, and the 

 weight and volume of ash determined, in order to learn 

 what amount of settling of soil was due to prairie fires 

 and what amount to drainage. These prairie fires have 

 rapidly changed a mesophytic area to a hydrophytic 

 one, extensive depressions occurring on the areas burned 

 over, and as the drainage of the ditches became more 

 sluggish, these depressions would fill with water, which 

 would scarcely dry up even in dry seasons. A number 

 of such areas came under the writer's observation be- 

 tween 1891 to 1897. In the latter year the outlet was 

 deepened by blasting the rock in bottom of ditch from 

 the point where the outlet empties into Spring Run to 

 the bridge just north of the Northern Ohio railroad sta- 

 tion. The point where deepening ended is shown in 

 figure 4, the rude fence marking the limit. 



