Fens

A fen may appear to be just another wet area, until you walk on it. What an opportunity to learn about this distinctive, rare wetland type found in Iowa. Fens are wetlands where groundwater comes to the surface, often causing the soil to behave in a “quaking” manner. Typically the water supports a range of plants that grow in inundated soil, such as upright sedge and Grass of Parnassus. Fens are generally associated with more recently glaciated regions of the upper Midwest. Northeast and northwest Iowa have some prominent fens that students might visit. Silver Lake Fen in northwest Iowa is a state preserve. Becky’s Fen and Rowely Fen in northeast Iowa are both accessible through county conservation board easements and land management agreements. These fens are associated with the most recent glaciation in the region. While most students are familiar with lakes, ponds, rivers, streams, and even marshes, a fen is a unique part of Iowa’s history that is important to include in learning about Iowa’s land and water. Fens are known to contain 12 species of plants that grow only in fen conditions and are classified as endangered.

• What causes the Earth to “tremble” in this way?

• How is a fen unique from other wetlands?

Students could:

• Look at landscape evidence and create their own explanation (argument). While they may not be correct or may need support, is a valuable process.
• Create an “I notice/I wonder” chart based on the phenomenon. 

• Geology of Iowa Fens: Great map (Figure 1)  for analysis to understand location of Iowa fens
• Iowa Geological Survey (IGS) | Landforms of Iowa: Students can compare this map of Iowa’s seven landforms to the fen map to determine the key characteristics that support creation of fens
• Iowa State University Extension: Landforms and Geology - Iowa's Nature Series: A free PDF booklet detailing Iowa geology, fossils and landforms.