[April, ’88. history society of Wisconsin. 
155 
The county is about 24 miles long from north to south and 
12 miles from east to west in its broadest part. 
The county is completely underlain by the Niagara forma¬ 
tion, which is common to the Lake Michigan shore of 
Wisconsin. In some places this formation is covered by 
the Lower Helderberg limestone, a shaly, almost pure 
dolomite, hard, brittle, of a light gray color and 
distinguished by numerous angular cavities which give it a 
porous structure. Both these formations, the Niagara and 
the Lower Heldeberg, are overlain in the extreme north-east 
comer of the county by a bluish gray, impure dolomite, the 
Hamilton Cement Rock. 
These paleozoic formations are covered with the drift of the 
second glacial epoch common to eastern Wisconsin. This 
drift is a gray pebble clay, replaced in the north-eastern part of 
the county by a red pebble clay of beach formation. The sub¬ 
soil covering this last is a red marly clay. In the south¬ 
west corner the subsoil is a light marly clay; and 
with the exception of a little humus subsoil and prairie 
loam which projects across the southern boundary 
from Racine County, the remaining subsoil of the county is a 
heavy marly clay. The soil in the north-eastern part of the 
county is a clayey loam, derived frpm the underlying red 
lacustrine clay. Throughout the greater part of the county 
the soil consists of medium and heavy loams. Humus soil 
occurs in a few isolated patches south-east and south-west. 
The soil of the south-west corner consists of light clayey 
loams. 
The altitude of the land above the level of Lake Michigan 
varies considerably. In the eastern half of the county it 
ranges from 1 to 100 feet, in the western half from 100 
to 200 feet and is still higher in the extreme south-western 
portions. The lake beach is bounded by bluffs, which aie 
interrupted for some distance at the mouths of the rivers. 
The principal stream is the Milwaukee lviver which enters 
