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 
a at i eee a 
Fig. 2.-TREE 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. 
