THE CLYDE SEEIES OF SOILS. 17 
While there are very extensive deposits of unquestioned lake sedi- 
ments within the area of the glacial Lake Saginaw, there are also 
numerous large areas where th.e glacial till remains uncovered by 
glacial lake materials or is so thinly covered that only portions of 
the present surface may be confidently ascribed to glacial lake depo- 
sition. Some of these deposits, because of the large amount of par- 
tially decayed organic matter in the surface soil and because of their 
evident previously swampy condition, are more closely related to 
the soils of the Clyde series than to any other group. Others, not 
so marked, belong to other soil series. The glacial outwash ma- 
terials and many of the beach line deposits do not contain sufficient 
organic matter to give them the characteristic dark color of the 
Clyde soils. 
Because extensive water-laid glacial moraines are closely asso- 
ciated with and partly covered by the glacial lake deposits some 
members of the Clyde series are found to be gravelly or stony in 
the Saginaw Lake area. 
In general the surface of the Lake Saginaw area is undulating to 
gently rolling, although considerable areas, extending northeast 
from Saginaw along the south shore of Saginaw Bay, are very flat 
and unrelieved. In consequence, a considerable proportion of this 
glacial lake area is fairly well drained through the deep-cut channels 
of the larger streams. Other portions, because of level topography 
and lack of natural stream ways, have remained swampy until 
recent years. 
Another glacial lake area of limited extent was formed in south- 
western Michigan, northern Indiana, northeastern Illinois, and 
southeastern Wisconsin around the southern end of Lake Michigan. 
This was known as the glacial Lake Chicago. The majority of the 
deposits within this area do not form soils which are included in the 
Clyde series. However, in a narrow belt extending along the west- 
ern shore of Lake Michigan from the vicinity of Kacine, Wis., 
nearly to Chicago, 111., the soils of the Clyde series occupy the greater 
proportion of the old glacial lake bed. In this area the soils of the 
Clyde series are found from the shore line of Lake Michigan to alti- 
tudes of 60 feet above its present level, at which elevation the shore 
line of the ancient glacial lake stood. This belt of territory ranges 
from 2 to 5 miles in width. The highest land within it frequently 
lies near to the present lake shore, declining gently inland for a 
distance of 1 or 2 miles and then rising rather sharply to the old 
shore line. At the higher elevations more sandy soils are found, 
while in the depression the soils of the Clyde series prevail. 
55812°— Bull. 141—14 3 
