Earth’s climate has changed several times in the past due to cyclical changes in the shape of earth’s orbit and tilt of its’ axis. Glaciers expanded to reach into the midwest a number of times. Glaciers reached all sides of the Driftless Area at different times, but are not known to have surrounded it completely at any one time.
Mickelson, David M.. GEOLOGY OF THE ICE AGE NATIONAL SCENIC TRAIL.. ©2011 by the Board of Regents of the University of Wisconsin System, Reprinted by permission of the University of Wisconsin Press.
>Retreating glaciers leave behind silt, clay, sand, gravel, and boulders – called drift. The southwestern area of Wisconsin has never been covered by glaciers and as a result it is called the Driftless Area. The northern and eastern lobes were in part diverted around the area by the Watersmeet Dome, an ancient uplifted area of Cambrian rock underlain by basalt.
The glaciers blunted hilltops and softened valleys with deposits which reduced the overall relief. As a result the Driftless Area has deeper valleys, steeper hill slopes, and narrower ridge tops than glaciated areas. Rivers in the Driftless Area carried large volumes of meltwater that undercut the bluffs and removed slope deposits. The only place erratics are found in the Driftless Area is in riverbeds. There are no natural lakes because there were no glaciers to leave blocks of ice behind to form kettles.
Bedrock in the Driftless Area is primarily 500-440 million year old sedimentary strata including sandstone, limestone, and dolomite. At Table Bluff, sandstone makes up the lower part of the ridge with Prairie du Chien dolomite on the top. Although the ridge is in the Driftless Area, the valleys around it were probably braided streams during the peak of glaciation. The accumulated outwash in the main valley measures 150 feet thick. Before the outwash was deposited, the valley was substantially deeper than it is today.
IATCC is the cache designation to highlight a series of EarthCaches along the Ice Age National Scenic Trail grouped into a special category called "ColdCache."
The Ice Age Trail is one of eleven National Scenic Trails designated by the National Park Service. This unique trail is entirely within the state of Wisconsin and follows along the terminal moraine of the most recent glacier which retreated about 10,000 years ago.
This project is supported by the Ice Age Trail Alliance (IATA). The goal is to bring more visitors to the trail and promote public awareness, appreciation, and understanding of Wisconsin’s glacial landscape.
The IATA has created an awards program to encourage visits to the trail and ColdCache sites. This awards program is separate from, and in addition to, any other Geo- or EarthCache awards program.
A current list of approved ColdCache sites can be found on the “IATCC Bookmark List”. More information on the Ice Age Trail Atlas, the Companion Guide, the ColdCache Project and Awards Program can be found on the “ColdCache Webpage”
The Geocache Notification Form has been submitted to Kevin Thusius of the Ice Age Trail Alliance.
Resources:
Geology of the Ice Age National Scenic Trail; by David M. Mickelson, Louis J. Mahler Jr., and Susan L. Simpson
Roadside Geology of Wisconsin; by Robert H. Dott, Jr and John W. Attig
Wikipedia
Logging Requirements:
- What is the elevation difference between the top and bottom of the bluff?
- There are several exposed rocks on and around the trail at the listed coordinates.
- How many exposed surfaces are in the immediate area?
- Do you believe the rocks are exposed bedrock or erratics? Why?