Bemidji August 2007

Focus on Environmental Geology

Big Bog State Recreation Area

One of the newest State Recreation Areas in Minnesota is the Big Bog State Recreation Area. The recreation area consists of two parts. The first is a campgrounds, beach, fishing pier and boat landing on the Upper Red Lake. The second is a section of the Big Bog, an area of about 500 square miles of peat and moss bogs north of Bemidji. The bog area has a "boardwalk" out into the bog where people can experience the wonderful plant life and bog features without destroying the bog with a walking path. In addition to the boardwalk there are other trails into this unique landscape. A State Recreation Area is similar to a State Park in Minnesota. The Big Bog is also listed as a Scientific and Natural Area which means it is part of a special natural area that the State DNR is trying to preserve for scientific study.
In 1891 government surveyors platted the area as a meadow. In the early 1900's drainage ditch soil provided the first road bed. A road linking Baudette and Kelliher was completed in 1914 and farmers started arriving to turn the bog into farmland.

At the edge of the bog the trees and brush grow taller. The boardwalk actually made from aluminum and plastic allow people to walk through the area that is almost always wet without damaging the bog. The slots in the boardwalk allow light to get through, giving the plants a chance to survive. The boardwalk is attached to posts much like a dock for a lake so that the bog is disturbed as little as possible.

In the photos below a DNR researcher shows a group of teachers how he does sampling of the moss and peat in the bog area. Notice that all the teachers are remaining on the boardwalk - you should also.

"Way down" is a sand and gravel base left by the glacier. Above that is a layer of mineral soil that is typical of farmland soil that is about 5,000 to 600,000 years old, rich in organic matter but not peat. It contains remains of plants that are not found in bog environments. Then the climate changed, became cooler and more humid, and a layer of peat formed from the dead plant material. On top of the peat is the layer of modern moss and other bog plants.


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Moss (photo at right) is the dominant plant in bogs and this bog is the largest in the lower 48 states. In some areas of the bog the moss is being harvested for many uses, especially for use in plant beds often sold at greenhouses. As the moss decomposes in the wet and low oxygen conditions of the bog it turns to peat (photo below). In many places in the world peat is burned for heat. Given enough time peat can be compressed into coal and under extreme pressures and temperatures even into diamonds.

The bog is home to many rare plants and of course many animals including bald eagles and moose. Early in Minnesota's political history it was even home to elk and caribou.

The photo at the lower right shows the results of an attempt to drain the bog and make it farmable. What looks like a grass walkway is the remants of a drainage ditch from about 1914. After almost 100 years trees and brush have still not filled in the abandonded area. The reason the State of Minnesota owns this land and much of the similar kinds of land is that farming attempts failed and the land was abandoned. The state reclaimed the land after the owners no longer paid the property taxes.

Most of the bog has very few trees. The trees that survive are black spruce and tamarac. They grow very slowly - some of the trees in these photos that are 6 feet tall may be over one hundred years old.

How does this connect to geology? The bog is in a lowland area that was once covered by glacial Lake Aggassiz. Lake of the Woods and the Upper and Lower Red Lakes are the main lakes that remain from this very large glacial lake. There is very little surface water between the Red Lakes and Lake of the Woods.

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