18 BULLETIN 141, U. S. DEPARTMENT OF AGRICULTURE. 



Surrounding Green Bay and Winnebago Lake and extending 

 southwestward past Fond du Lac, Wis., occurs another area which 

 was occupied by glacial lake waters. The highest shore line which 

 bounds this area lies at a level of 800 to 820 feet above sea level, or 

 220 to 250 feet above the present level of Lake Michigan. In general, 

 the surface of the lake sediments in this area is level or gently undu- 

 lating, although ridges of till rise above the lower lying glacial lake 

 material. As in the case of the western New York areas and the 

 Saginaw Bay area, other glacial lake sediments occupy considerable 

 areas within this region, yet the lower, more level, and poorly drained 

 sections where organic matter has accumulated extensively are occu- 

 pied to some extent by soils of the Clyde series. As in the case of 

 the majority of the other localities where soils of this series are 

 found, limestone rock underlies a considerable proportion of the 

 glacial lake embay ment around Lake Winnebago and Green Bay. 

 It has been reworked to some degree into the glacial till and into the 

 glacial lake sediments derived from the till. 



It is probable that an examination of the Upper Peninsula of' 

 Michigan will show small areas of the Clyde soils lying at the lower 

 levels around Lake Huron and along the southern shore of Lake 

 Superior. The necessary conditions of local calcareous rock, of 

 glaciation, and of the deposition of glacial lake sediments followed 

 by swampy conditions after the withdrawal of glacial lake waters 

 all exist in the eastern end of the northern peninsula of Michigan. 



The occurrences of the Clyde series thus far outlined all lie within 

 the larger glacial lake basins surrounding the present Great Lakes. 

 In addition there are hundreds of smaller glacial lakes which existed 

 in the upland areas, outside of these larger basins, in western New 

 York, southern Michigan, northern Indiana, and southern Wiscon- 

 sin particularly. In many instances these small glacial lakes have 

 become drained or have been partly filled with accumulations of both 

 mineral and organic matter. In such instances smaller areas of the 

 different soils of the Clyde series have frequently been formed. 

 Such is the case in many of the southern counties of Michigan and 

 of the southeastern counties of Wisconsin. 



Another characteristic mode of occurrence of the soils of the Clyde 

 series is found along the old glacial drainage lines through which the 

 ponded waters of large and small glacial lakes found their outlet 

 across the divides. In many instances these drainage channels now 

 exist as bread river valleys cut through the glacial till where the 

 present streams are bordered by one or more broad, flat, and fre- 

 quently poorly drained river terraces. Wherever drainage has been 

 sufficiently obstructed to give rise to temporary swamp conditions 

 there has been considerable accumulation of swamp vegetation, con- 

 tributing organic matter to the surface soil. In some instances this 



