The core of the field trip began about 7 am on June 23. Dr. Annexstad began with a story of how Lake Bemidji was used to test C130 cargo aircraft with skis to determine if they would work for landing on Antarctica.
|Much of the trip between Bemidji and Grand Rapids was in a drainage way for the Wadena Lobe of the of the Wisconsinan glaciation period. The remnants of the glaciation are the outwash sediments that form the topsoil, rivers and lakes of the region that are visible on the map. So much water was released by the melting glacier that specific channels were not established for some time forming many valleys and braided streams in addition to the main channel that became the Mississippi River. Today roadways are often built in or along these channels. Some of the lakes that were left are called Oxbow Lakes as the drainage channel changed course and left behind a bend in the river that became a lake.|
section bedrock map of Minnesota is a good resource to have handy
throughout this virtual field trip. Looking at the small maps of the
state (black) one should see a white line going from the north to the
south with a slight angle to the east. As one lookes at the larger maps
the bedrock indicated follows this line with the left side being the
northern most part and the right the southern most part.
The swamp or bog areas can be
from the road by the lack of significant tree vegetation. Where
ground is saturated with the water the vegetation is poor because of
lack of minerals in the soil. Many areas have 40 to 50 feet of
that has been deposited in the last 5000 years. Peat is the
to coal and it is estimated that five to six feet of peat to get one
of coal. Wyoming has some coal beds that are over 100 feet
By the time we get to the city of
Deer River we are beginning to see outwash sediments from the St. Louis
Sublobe which is still part of the Wisconsinan glacial period but
much later than the Wadena Lobe. We are in an area that has
ground moraines or cover moraines that occur underneath stagnant
The stones and rocks are well rounded and are mixed with silt and clay.
At our first stop which is near
town of Taconite, we will see evidence of the mixture of material of
Wadena lobe that came from the north and the St. Louis Sublobe that
from the northeast. This is near the edge of the glacial lake
and glacial lake Aitkin. From Grand Rapids to Taconite we will
gently rolling terrain that is the end moraines of the St. Louis
The material left by the glacier contains all kinds of unsorted
that is both rounded and angular. Grand Rapids is also on the
edge of the Mesabi Iron Range that is defined by the Animikie Basin.
1. Ojakangas, Richard W. & Matsch, Charles L.; Minnesota's Geology, 1982, p18