HUBON COUNTY. 297 



When horizontal roots are well developed the tree is safely anchored, and 

 is in no danger of being thrown out by the frost.' So the stumps of dead 

 trees remain undisturbed by the frost until the horizontal roots have 

 rotted away. After that those having large top roots are rapidly lifted 

 out of the soil by the action of the frost. I have repeatedly seen such 

 swamps, with the remains of the horizontal roots two and three feet 

 above the surface, and others that had fallen down, having been com- 

 pletely lifted out of the ground by the action of frost. In the elevation 

 of these bowlders the frost may have had some influence, but it was 

 probably slight. It is not necessary to assume that the trunks of the 

 trees were here elevated by the growth of the roots, though it is proba- 

 ble that they were. If we may assume the fact that the horizontal roots 

 would pass under these bowlders, and maintain their normal growth 

 under the pressure, their slow and steady elevation would follow as a . 

 necessary result. 



Remains of other sand ridges than that described can be detected in 

 other parts of the county. Between Norwalk and Olena, on the line 

 which separates Bronson and Hartland townships, the surface presents 

 to the eye the appearance of a broad, level plain of rich sandy loam, 

 but it rises imperceptibly to the height of two hundred and fifteen feet 

 above the sand ridge at Norwalk, or three hundred and sixty feet above 

 the Lake. This originally supported a dense forest of oak, hickory, black 

 ash, elm, etc. About one mile east of Olena a long, sandy and gravelly 

 ridge rises to the height of three hundred and ninety-five feet above the 

 Lake. It has a nearly north and south direction, sloping on the west 

 gradually to the general level of the plain, and descending abruptly to 

 it on the east, the top being thirty-five feet above this general level. 

 The materials here have been assorted by the waves and wind in the 

 same way as those of the northern ridge. 



Near the north-east corner of Hartland township there are also the 

 remains of another sand ridge, fifty feet lower than the last, which has 

 suffered much from erosion, and is cut up by very irregular valleys lead- 

 ing down to the west branch of Vermillion River, exposing the coarse 

 Drift below, with'many large striated bowlders. 



In the western part of Fitchville township a long, sandy ridge, trend- 

 ing nearly north and south, rises in the highest parts to four hundred 

 and twenty-five feet above the Lake, rising ten to fifteen feet above the 

 level land to the east, and twenty to twenty-five feet above that on 

 the west. The land to the north-west of this is a plain, diversified by 

 irregular sand ridges and dunes descending gradually to a lower level, 

 and marl^ing the gradual descent of the waters of^the old lake. On these 



