What are Terminal Moraines
Terminal Moraines are ridges left behind from glaciation.
Illinois has multiple Moraines such as the Moraine at Moraine Hills State Park and the Shlbyville
moraine amongst others. Far from being flat and featureless,
glaciation has left Illinois a very geologically diverse state.
How Moraines Form
From the ISGS:
Melting at a glacier margin causes the ice to thin, and
ground-up rock debris carried in the base of the ice or dragged
along beneath the glacier is deposited. When the ice margin remains
in the same place for a relatively long time (tens to hundreds of
years), enough debris flows to the glacier's leading edge and piles
up to form a large end moraine on the landscape.
Formation Period
The Shelbyville Moraine formed during the Late Wisconsin period
of glaciation around 23,000 years ago.
What Are They Made Of?
Moraines are typically made up of till that consists of sand and
gravel.
Beginning and End
The Shelbyville Moraine reaches from Western Indiana to
Shelbyville where it turns northward toward Peoria. This moraine
marks the outer reaches of the Wisconsin glaciation period.
Other Features
The height of the Shelbyville Moraine varies from 50 to 100 feet
above the surrounding glacial plain. The view of the Shelbyville
Moraine is much more prominent when viewed from the south, rising
somewhat suddenly and gently molding into the northern landscape,
making a view from the north much less noticeable.
To Earn a Smiley
To earn a smiley for this earthcache please answer the following
questions, email the answers to the owner do not post them in your
log:
- What geologic feature breaches the moraine in the general area
of the coordinates given?
- How has man used the natural features of the moraine to his
advantage in the area of the given coordinates?
- Using the text above and the provided images what would be your
guess as to the southern reaches of Illinois glaciation?
- Optional but encouraged send an image of your cache crew at the
cache location.