Both Lake and Porter County comprise three distinct geologic and physiographic regions:
- the Calumet Lacustrine Plain
- the Valparaiso Morainal Area
- the Kankakee Outwash and Lacustrine Plain
Vocabulary:
- Lacustrine - Lake Deposits
- Moraine - a ridge, mound, or irregular mass of unstratified glacial drift, chiefly boulders, gravel, sand, and clay.
- Outwash - the material, chiefly sand or gravel, deposited by meltwater streams in front of a glacier.
This cache will focus on one element of the Calumet Lacustrine Plain
These geologic features listed above are the byproduct of the Wisconsinan Age of glaciation, the most recent in glacial advances, which occurred between 85,000 and 11,000 years ago. This glacial movement radically altered the region north of the Ohio River, forming much of the landscape we see today. As the massive glacier receded it left behind the predecessor of Lake Michigan called Lake Chicago. The Southern boundary of this large lake deposited large banks of sand and silt, forming the moraine we call The Ridge over a period of 10,000 years. The Lake was over 600 feet above sea level when its southern boundary was the area of the Ridge. Over the next thousand years, the water receded to roughly 15 feet, leaving the Ridge behind as a lasting landmark of Lake Chicago.
The Ridge runs parallel to the shoreline of today's Lake Michigan and is a distinct landmark to the ancient Lake Chicago. The regional topography remained largely unchanged until the late nineteenth century when settlers started using the high ridge to travel westward because the lower laying areas north of the ridge were filled with reeds, tall grasses, and other thick vegetation making travel difficult. The Ridge extends from Gary westward into Lansing where it tapers off into the Kankakee Lacustrine Plain.
Unlike the Calumet Lacustrine, the Valparaiso Morainal Area was formed while the glacier was much weaker. By the time the glacier reached the Valparaiso area, it had become weak. When it encountered large deposites of dolomite it did not advance, depoisting large amounts of sand and silt. This formed the hilly landscape Valparaiso is known for.
When the glacier finally halted in the Valparaiso Morainal Area, it slowly began to melt. This runoff washed westward forming the Kankakee Outwash Plain. Because of a drop in elevation between Valpariso and Kankakee, the muddy runoff eventually eroded any hills and valleys, flattening out the surrounding area forming a plain.
These three artifacts of the Wisconsinan Age of glaciation are all distinct from themselves. Each of these zones were all formed from from the same glacier, with unique characteristics depending on their location; the Calumet Lacustrine, which was formed when the glacier carved the land underneath it, the hilly countryside in Valparaiso which was formed as the glacier halted it's advance, and the Kankakee Outwash Plain, which provided a runoff zone for the melting glacier.
To log this cache:
In an email please answer the following questions based on your personal observations:
Do not post answers as part of your log, encrypted or otherwise, or it will be deleted!
- At stage 1 what is the elevation? Looking North, would you say the area is fairly flat or hilly?
- At stage 2 what is the elevation?What does the topography look like today? Looking North and South, is there any differences in the topography?
- As you walk from Stage 2 to Stage 3, is there any evidence of sand and silt left behind by Lake Chicago?
- At stage 3 what is the elevation?Looking South, would you say the area is flat or hilly?
- At stage 4 what is the elevation?
- Compare the elevation at stage 1, 2 and 3. What is the difference in elevation? Would you say Lake Chicago's shoreline was deep or shallow?
- Optional: take picture of yourself at any of the stages.
Got your answers? Click Here to send me your answers
Don't wait for a reply to log it, I will typically only reply to incorrect answers and delete logs from users who did not send an email.
Sources:
- Handbook of Indiana Geology
- Environmental Geology of Lake and Porter Counties, Indiana
- How the Ice Age Shaped Indiana
- wikipedia
|
|
Congrats to
j3yoda
for being the FTF!!! |