From the top of this 500-foot bluff, the
confluence of the Wisconsin River and the mighty Mississippi may be
seen to the south. To the north, the view of the bridges connecting
Iowa and Wisconsin is breathtaking.
Pikes Peak State Park is located in the
"Paleozoic Plateau" that was missed by the glaciers that flattened
and molded so much of Iowa. This area, often called the "Driftless"
region, is noted for its natural beauty. Its hills and valleys
offer great vistas, large timbered tracts, spring-fed streams and a
natural beauty unique to northeast Iowa.
The melting of those enormous ice sheets that, at their maximum,
were 5,000 to 10,000 feet thick and covered hundreds of thousands
of square miles, released tremendous amounts of water, forming huge
glacial lakes. The largest of the glacial lakes, Lake Agassiz,
covered northwest Minnesota, parts of North Dakota and the Canadian
provinces of Manitoba, Saskatchewan and Ontario. The southern
discharge outlet to this lake was called Glacial River Warren,
which eventually excavated the valley now occupied by the Minnesota
River. (The Mississippi River flows into the valley carved by the
River Warren at St. Anthony Falls in Minneapolis.)
The St. Croix River which drained Lake Duluth, a glacial lake that
covered the western Lake Superior basin, joined the River Warren
about 30 miles downstream from the present confluence of the
Mississippi and Minnesota Rivers. In Wisconsin, another glacial
lake drained first into what is now the Black River and later the
Wisconsin River, both of which emptied into the River Warren.
During the 3,000 years that River Warren carried water from these
and other smaller glacial lakes, the Mississippi River valley was
carved bluff to bluff and the resulting valley was approximately
250 feet deeper than it is today.
However, there is also evidence that the main valley is much older
than the River Warren and underwent several cycles of cutting and
filling during the Great Ice Age. Even though the Coulee country
escaped the land-leveling effect of the ice mass, the glaciers left
their mark by carving the spectacular Mississippi River that cuts
through the heart of this area with the torrents of water draining
from the melting ice mass.
To receive credit for this
EarthCache, you will need to complete the following
tasks.
In an e-mail to me, please
tell me the following:
1. Across this gorge of the Mississippi
River is the Wisconsin River. Please tell me what type of rock the
river valleys are carved into.
2. Where did these layered rocks
originate? Is there any evidence that these rocks originated
there?
3. Approximately when did the geologic
event end that formed these valleys?
4. Please describe how strong the
current must be at this point in the River. (think of how much of a
bend you see, how deep is the valley?)
And
5. When you log this EarthCache, please
upload a picture of yourself/team with your GPS clearly visible
with the river valley in the background.
Please Note. Logs
that do not meet these five criteria
Will Be Deleted- No
Exceptions!