Figure 27

MAP AND CROSS-SECTION OF E
W~ SI  GTNCU T   ZAKE
I  un
WASHINGTON COUNTY r
OZAUKEE
COUNTY
J I WUEH          ONY
S
i~ N -OmI
F  --  ----
/ /           *RACINE COUNTY
/1WALWORTH            >
KENOSHA COUNTY  0
Source: SEWRPC.
River, Oak Creek, and Pike River watersheds, are
wholly contained within the Region. In addition
to these 11 major watersheds, there are numerous
small catchment areas contiguous to Lake Michi-
gan that drain directly to the lake by local
natural watercourses and artificial drainage-
ways. Together, these areas may be considered to
comprise a twelfth watershed. The drainage in
the Region tends to exhibit a disordered dendritic
pattern except for a small area of trellised or
rectangular drainage evident in the Des Plaines
River watershed and in the Racine County
portion of the Root River watershed. The Fox
River watershed and the headwaters of the Rock
River and Des Plaines River watersheds drain to
the south and southwest toward their confluences
with the Illinois River, a tributary of the Missis-
sippi River. The remainder of the Region drains
in a generally easterly direction toward Lake
Michigan by way of the Milwaukee, Menomonee,
Root, and other drainages.
GEOLOGY

Knowledge of bedrock and of the surficial
deposits overlying the bedrock is important to

BEDROCK GEOLOGY IN THE REGION
SECTION AA
GEOLOGIC SECTION THROUGH
MILWAUKEE ANDWAUKESHA COUNTIES
z zI
800                0
PLEITOCNE  ND
Om            n
-400 -
-8 LE EL-0-
-400
-soo -         -                 <-

1200
800
400
SEA LEVEL
-400
-800

LEGEND
FmMILWAUKEE FORMATION
Sn NIAGARA DOLOMITE (LANNON STONE)
FmMAQUOKETA SHALE
u PLATTEVILLE, DECORAH,AND GALENA FORMATIONS UNDIFFERENTI ATED
SANDSTONE OF CAMBRIAN AND ORDOVICIAN AGES
pe PRECAMBRIAN CRYSTALLINE ROCKS
land use, transportation, and other public
facility and public utility planning. Bedrock
conditions and the overlying surficial deposits
directly affect the construction costs of such
urban development projects and supporting
public works facilities as streets and highways
and public utilities, particularly those involving
extensive trenching or tunneling. Moreover, the
placement of urban improvements in relation to
the bedrock and surficial deposits may directly
or indirectly affect the quality and quantity of
the groundwater resources of the Region.
Bedrock
The bedrock formations underlying the uncon-
solidated surficial deposits of southeastern
Wisconsin consist of Cambrian through Devo-
nian Period rocks of the Paleozoic Era that
attain a thickness in excess of 1,500 feet along
the eastern limits of the Region, which are in
turn underlain by older, predominantly crystal-
line rocks of the Precambrian Era. The bedrock
geology of the Region is shown in Figure 27 by
means of a map of the surface of the bedrock
supplemented by a representative vertical
section.

109