Near the end of the last Ice Age in North America, Glacial Lake
Agassiz was created when glacial melt water ran into ice retreating
northward. The ice acted as a dam and Lake Agassiz formed over the
Red River Valley and Northern Minnesota, at one point covering over
170,000 square miles.
The Minnesota State University Moorhead Regional Science Center
land and adjacent Buffalo River State Park are located on what used
to be the eastern shores of Lake Agassiz. The Buffalo River
originally drained into the lake, but since Agassiz dried up 8000
years ago, it has been cutting into the ancient lake shores as it
flows downhill into the Red River west of here.
To get there, follow US Highway 10 out of Fargo-Moorhead and
follow the signs to the Buffalo River State Park (about 14 miles
east). After turning off US 10, take a left immediately after the
railroad underpass. Signs will point the way from there. The
trailhead is on the east side of the parking lot (Coordinates N46
56.020 W096 27.195). Do not cross the river, stay on the west
side.
When you reach the cache coordinates, you will see much of this
history in front of you on the opposite bank. The river is cutting
though that bank, exposing the layers and deposits. There are four
distinct layers (in no particular order, yet):
A) Tan colored sand and gravel deposits. These were left by the
river when it was at a different level than it is now. Notice the
layering of the gravel deposits due to the sorting action of the
river. You can see this happening in front of you in the river
today.
B) The topsoil. This one is fairly obvious, showing a nice
cross-section of what the prairie looks like under your feet now.
It is a mixture of minerals and decayed organic matter. The soil in
this region is a nice black color, indicating the fertility that
makes it famous.
C) Glacial till, which is grayish in color. These are sediments
deposited by the glaciers as they retreated.
D) The B horizon of the soil. This contains mostly minerals,
without the concentration of organic matter that the topsoil above
it has. In this area, the B horizon tends to be fairly dense
clays.
To get credit for this Earthcache, email me the
following two items:
1) The correct order of the layers starting at the top of the
cutbank and working down to the current river level.
2) Since the trail and waypoint are on the bank opposite the
cut, figure out which layer you are currently standing on based on
what layer you are even with across the river.
This cache was placed with the help and permission of the staff
of the MSUM Regional Science Center. The site and trails are free
and open 6am to 11pm everyday. In the winter, feel free to bring
out cross country skis or snowshoes.