498 TH GEOLOGY OF MINNESOTA. 



[Soil and timber. 



depth of about two feet below the surface by decaying vegetation. Un- 

 modified glacial drift or till, the same as the soil, excepting that it is not 

 enriched and blackened by organic decay, continues below, being yellowish 

 gray to a depth of 10 or 20 feet, but darker and bluish beyond, as seen in 

 wells. This deposit contains many fragments of magnesian limestone, red 

 quartzyte, granites and crystalline schists; and its fine detritus is a mix- 

 ture of these rocks pulverized, presenting in the most advantageous pro- 

 portions the mineral elements needed by growing plants. Wheat has been 

 the principal crop, but stock-raising has also received much attention in 

 Jackson county during several years past. A large variety of crops is 

 profitably cultivated throughout this region, including wheat, oats, corn, 

 garden fruits and vegetables, potatoes, and hay. In general, Jackson and 

 Martin counties have a somewhat more sandy soil than the districts adjoin- 

 ing them on the east, north and west, and appear to be therefore slightly 

 less adapted for wheat-raising. Besides this staple product, horses and cat- 

 tle, pork and beef, butter and cheese, have become considerable exports. 



From 1873 to 1876 Cottonwood and Jackson counties, in company with all southwestern 

 Minnesota, were distressed by the ravages of the Rocky Mountain locust. To many the work of 

 plowing and sowing, and the wheat sown, were total losses during these years. In 1880 frequent 

 groves were noticeable between Fairmont and Worthington, which had been set out to shield 

 farm-houses from the wind, and still remained, though the buildings were gone and the farms 

 deserted, telling where in this struggle the grasshoppers had conquered. Though the wheat was 

 nearly everywhere eaten by them so that no harvest could be saved, the prairie grass suffered 

 only slightly, and from this epoch herding has taken an important place in the agriculture of 

 Jackson and Martin counties. 



The opinion prevails, and seems to rest upon a correct knowledge of facts, that the yield of 

 wheat generally in the southern tier of counties of Minnesota during the past fifteen years 

 or so, averaging ten to fifteen bushels per acre, has been only half or two-thirds as great as dur- 

 ing the preceding ten or fifteen years. Much land remains that was never broken with the plow, 

 and this contrast in productiveness is exhibited by newly broken ground in all respects similar 

 to adjacent tracts that were first cultivated twenty or thirty years ago. It appears also that the 

 early immigrants found wetter seasons, the sloughs more frequently impassable, and the lakes 

 mostly standing at somewhat higher levels, than during the fifteen years next before 1880. To 

 differences in rain-fall thus indicated, and differences in temperature and winds, and in their 

 distribution through the year, making up the climate as a whole, we must attribute the diminu- 

 tion in the wheat crop. Probably these general climatic changes will be found to be periodic; 

 lessened precipitation of rain and snow, and reduced yields of wheat through several years, being 

 succeeded by a term, perhaps of equal duration, bringing as great rainfall, and as plentiful har- 

 vests, as have ever been recorded. The more wet years from 1880 to 1882 may mark the begin- 

 ning of a period especially favorable for wheat-raising in southern Minnesota. 



These counties are natural prairie, affording rich pasturage, and ready 

 for the plow. Less than a hundredth part of their area is wooded. This 

 includes small groves and narrow skirts of timber and brushwood about 



