This illustration shows the Wisconsinan glaciation. At the height
of the Wisconsin glaciation, ice covered most of Canada, the Upper
Midwest, and New England, as well as parts of Montana and
Washington.
In its retreat, the Wisconsin glaciation left terminal moraines,
drumlins and eskers. The Wisconsin glaciation also left something
that you will find at these coordinates.
Northeastern Iowa has a significant concentration of boulders
across the landscape, and the greatest number of exceptionally
large erratics. This region, known as the Iowan Surface, was once
much like southern Iowa, with loess deposits mantling steeply
rolling terrain composed of glacial materials deposited in Iowa
over 500,000 years ago. About 20,000 years ago, extremely cold
climatic conditions led to erosional beveling of this area and
removal of much of the finer-grained glacial materials, thus
concentrating the larger pebbles and boulders at the land
surface.
To claim credit for this EarthCache you
must do the following four things:
In an e-mail to
me:
1. Describe the height of the glacial erratics at the
given coordinates.
2. Please describe the surface texture to me (is it
rough, smooth, etc?)
3. Find another example of a glacial erratic in the area.
(They are not hard to find at all, as a matter of fact, the largest
glacial erratic in the entire State of Iowa is less than .5 miles
from these coordinates.) In the same e-mail give me the coordinates
of the boulder you found.
and
4.When you log this EarthCache, please upload a picture
of yourself/team with the glacial erratic you found with your GPS
clearly visible.
Logs that don't meet these four requirements Will Be Deleted-
No Exceptions!
Please note! There are plenty of glacial erratics located
on public property throughout this part of Northeastern Iowa (such
as the boulders at the listed coordinates).Do not venture on to
private property in search of erratics without the property owner's
permission.
This is a photo circa 1935 showing St. Peter's
Rock.
I'd like to thank DuHawks for allowing me to
use this special picture.