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, j r et 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 embayment 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 cf 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 
