636 THE GEOLOGY OF MINNESOTA. 



[Soil and timber. 



Washington, 975; Le Sueur, 810; Ottawa, 860; and Kasota, 880. The mean 

 elevation of the county derived from these figures is 985 feet above the 

 sea. 



Soil and Umber. The black soil of this region has generally a depth of about two feet. It 

 is clay with some admixture of sand and gravel and occasional stones and boulders, being the 

 upper part of the glacial drift, colored by vegetable decay. Below this black stratum, the subsoil 

 is the same gravelly clay, yellowish for the next ten or twenty feet, and then darker and bluish to 

 a great depth which is seldom passed through by wells. 



In the fertility of its soil and its agricultural capability Le Sueur county is the peer of any 

 in Minnesota. The undulating surface causes the water of rains and of snow-melting to be soon 

 drained away, excepting the portion which the soil absorbs to be given out for the growth of 

 plants. Perhaps a tenth part of this county is occupied by its abundant lakes, its equally numer- 

 ous but smaller marshes, which are not wooded and bear excellent wild hay, and by the bluffs and 

 ravines of streams; the remaining area ( excepting occasional small tracts of the moraines, more 

 than ordinarily knolly and stony) is adapted for cultivation. The staple crops are wheat, oats, 

 barley, corn, hay, flax, sorghum, potatoes, and the common vegetables and small fruits of the 

 garden. 



This county lies within the southeast part of the extensive forest, a hundred miles long from 

 north to south and forty to fifty miles wide, which is commonly called the Big Woods, being a 

 southern lobe of the great wooded region of northern Minnesota and British America. Heavy 

 timber originally covered the whole county, except small tracts of marsh, which would be called 

 sloughs in a prairie district, and certain areas in the Minnesota valley, as the Le Sueur prairie 

 and the terrace of limestone south of Kasota. Since the first immigration, some twenty-five years 

 ago, much of this timber has been cleared off and the land brought under cultivation, the stumps 

 being got rid of within ten years by burning and pulling, leaving the fields smooth for the plow 

 and the reaper. The principal kinds of trees found here are bass, sugar maple and soft maple, 

 box-elder, wild plum, the wild red cherry and black cherry, American crab-apple, Juneberry, 

 white and black ash, white or American elm and slippery or red elm, hackberry, butternut, black 

 walnut, bitternut, black and bur oaks, ironwood, water beech, paper or canoe birch, common 

 poplar or aspen, the large-toothed poplar, cottonwood, and (rarely) red cedar. The last two occur 

 mostly beside rivers and lakes. Nearly everywhere through this forest, its two largest and most 

 plentiful species of trees are the bass and the white elm. Its shrubs include prickly ash, smooth 

 sumach, frost grape, Virginian creeper, climbing bitter-sweet, red and black raspberries, wild 

 rose, thorn, choke-berry, prickly and smooth gooseberries, black currant, two or three species of cor- 

 nel, wolfberry, honeysuckle, elder, sweet viburnum, high-bush cranberry, hazel-nut, and willows. 



GEOLOGICAL STRUCTURE. 



Jordan sandstone and Shakopee limestone. The only exposures of the bed- 

 rocks of this county consist of two members of the Lower Magnesian or 

 Calciferous series, namely the Jordan sandstone and the overlying Shako- 

 pee limestone, which form terraces about 75 feet high in Kasota and Otta- 

 wa, within the valley of the Minnesota river. Fluvial erosion, since the ice 

 age, has excavated this great channel through the sheet of till which forms 

 bluffs on each side of the valley 150 feet above these rock-formations; but a 

 river that flowed here long before the ice age, had cut deeply into the rocks 

 and sculptured them nearly as they are now seen. Their terraces are pro- 

 duced by the persistence of the hard limestone lying above the soft and 



