16 



Hvets. The Wmoval of the natural turf or sod of the prairies has the same 

 feffect upon the soil, especially in those districts where the particles are fine, 

 and therefore more easily suspended in water and washed away by the rain. 

 Even the slight interruption of the proteotihg vegetable carpet, caused from 

 an Indian trail, is often sufScient to cause frightful gullies in a very fe# 

 years. All steep hill-sides ar6 liable to this evil when the trees or the sod 

 are removed. On the margin of the steep banks of lake Michigan these 

 deep gullies are formed, making it necessary to remove the " lake shore 

 road " from time to time farther from the water. Advantage is often taken 

 of this process) to secure the filling of village lots in low grounds, by direct- 

 ing the earth-bearing currents upon them, and thus avoid the far more ex- 

 pensive mode of filling by the intervention of a " contractor." The curious- 

 ly shaped mounds of earth representing animal and even human forms, left 

 by the former inhabitants, could not have been preserved to puzzle the brain 

 of the modern antiquary, but for the protection of the matted roots of the 

 forest trees or of the prairie sod-, with which they have been covered. When 

 these are removed, the form of the mound is soon lost by the wash of rains. 



We hence see that trees are required, especially on steep side-hills, and 

 where the soil is light, to protect, by their roots and otherwise, the very soil 

 from being dissolved and carried away by rains. 



To realize the importance of this constant absorption of the soil, we have 

 only to refer to the deep and broad valleys every where excavated, and to 

 the deltas of large riverS) where whole states owe their very existence to the 

 accumulations of earthy matter brought down from their channels above, 

 including among its particles the richest soil of the uplands. The quantity 

 of sand and mud carried into the Mississippi river by the principal tributaries 

 from this state, especially the Wisconsin and Chippewa, is such that the cur' 

 rent of this great river is checked in its onward flow, and formed into lakes. 

 With the exception of Lake Pepin, immediately above the bar caused by 

 the Chippewa river, these lakes have already been completely filled by the 

 moving sands from above. This lake remains, only because the supply of 

 earthy matter from, above is less abundant, and requires longer time to ac 

 complish the object. Already has the amount of eartjiy matter, brought into 

 the Mississippi river from the surface of our state, been so much increased, 

 by the destruction of the forests, and the breaking of the sod, that it begins 

 to disturb the former condition of things; the water is no longer clear and 

 dark, from decomposed vegetable matter, as it used to be , more sand accu- 

 mulates in the stream, and a noticable quantity of saw-dust and chips from 

 the lumber regions of the St. Croix, Chippewa and Wisconsin is also deposited 

 along the banks. So important is this action deemed by competent cngi- 

 neers, that' it is mentioned in a recent government report, as one requiring 

 attention; though the gradual rise of the bed of the river, occasioned by 

 these increased deposits, maybe So slow that its effects may, for the present, 

 be idisregardedi 



