BIG SPRING PRAIRIE. 



29 



present, they are at a loss how to account for the fact, 

 as the muck in those identical places is now only three 

 or four feet deep. Below the muck, there is either a 

 sand bed, a layer of clay or both. The testimony of 

 the bowlders clears the mystery, for the muck was 

 formerly deeper, and the sand-layer beneath was a 

 quicksand, such as is yet encountered while making 



Fig. 2.-TEBB With Exposed Roots, Showing Settling Soil. 



excavations for the abutments of some of the bridges 

 across the prairie streams. When thoroughly drained^ 

 the quicksand becomes a solid bed. The settlers^ 

 ignorant or unmindful of the quicksand beneath, 

 were mistaken in supposing that the entire depth 

 penetrated was muck. 



As further evidence of the amount of settling of 

 the soil, we would direct your attention to figure 2. 



