PLATE XXXVII. 



McLEOD COUNTY, 1888. WARREN UPHAM. 



The geology of this county is restricted to the glacial deposits, there being no 

 outcrop of the underlying rocks within its limits. It is wholly flat or gently undu- 

 lating, and these features in the prairie region are continued into the wooded region. 

 About one-half of the county (the northeastern) is thickly wooded with deciduous 

 trees, and in the rest of the county are scattered groves of stunted oaks and of young 

 poplar. The "big woods" run out into the prairie by passing through an increas- 

 ingly loose fringe of small timber, mostly oak and poplar, which has a width of half 

 a mile, or of two or three miles. It is apparent to the traveler that the width, as 

 well as the density, of this fringe depends on the facility with which it can be 

 attacked by prairie fires moving from the west, and that, in general, the prairies are 

 due to the action of such fires. West of this fringe such groves are confined to the 

 protected eastern sides of lakes, or to the banks of the streams. 



Throughout the county the drift consists essentially of till, having a thickness 

 from 100 to 200 feet; but it is divided in some places into at least two parts, which 

 are separated by a stratum containing shells and trees, showing that interglacial 

 epochs occurred, during which animal and vegetable life flourished. This is in accord 

 with the deductions already stated as to the history of the Minnesota valley and as 

 to the interglacial peat deposits of Mower and other counties. 



Cotemporary with the accumulation of the gravel terraces of the Minnesota 

 valley, or slightly later, similar gravel deposits were formed by the local washing of 

 the till at other places. Some such are found in the gravel plains and knolls in 

 McLeod county seen in Hutchinson and Helen. They probably exist in many other 

 places not discovered, concealed by the uniform black soil that covers the whole county. 



The deep 'well at Glencoe, sunk in 1896 and 1897, has a depth of 1,640 feet, and 

 supplies abundant good water for the city, but does not overflow. According to 

 drillings and record furnished by Mr. T. M. Paine the well passed through the follow- 

 ing formations: Drift, 168 feet; St. Croix, including the St. Lawrence and some red 

 shale, 387 feet; Hinckley sandstone, 381 feet; Fonddu Lac sandstone, 157 feet; Pots- 

 dam red quartzyte, with beds of red shale (catlinite), 315 feet; red shale and sand- 

 stone, 230 feet; bottom of the well at 1,640 feet. 



This record is important, as it shows the position of the Potsdam quartzyte (seen 

 at Courtland, in Nicollet county) to be in the midst of a great sandstone formation. 

 The place of the Manitou trap is represented, probably, by the red shale and sand- 

 stone that occur above it, and the Cabotian by the great shale and sandstone forma- 

 tion that lies below it. The well did not go deep enough to reach the Animikie. 



