Karst Topography & Spring-Fed Waterfalls

Grannis Creek falls is a moderate sized spring fed stream in the karst topography of the Driftless Region of northeast Iowa. It is a dramatic example (for Iowa) of fractured bedrock creating cool spring fed streams characteristic of the Driftless landscape.  

Possible Guiding, Compelling and/or Anchoring Questions

• Where is the water coming from?
• How does the area of the spring differ from the surrounding landscape?
• Why is the spring area so different looking from the rest of the hillside? 
• Really, where is that water coming from? (walk ‘upstream’)
• How could events at the top of the hill impact the water we see coming out here?
• What needs to happen within the ground to allow this phenomena to occur? 
• Why are Iowa’s trout streams found in northeast Iowa? (The stream in this video is stocked with trout.)
• How does this spring help keep trout alive, when they won’t survive in other parts of the state?

Classroom Suggestions

• This phenomena could be used to highlight karst topography, sinkholes, springs, disappearing streams and why trout fishing is found in Northeast Iowa.
• Students could use it to begin investigation in bedrock formations, chemical weathering of rocks, cave formation, & a multitude of topics related to ground water - these could include water pollution, water oxygen, soil erosion, nutrient pollution, and ag practices. 

Related Resources

• Karst and Water Pollution Lesson Plans: PDF file produced by the state of Minnesota with several lessons about Karst topography. Many are written for grades 6-8, but they could be adapted for other levels. 
• Iowa DNR Trout Fishing Map: This interactive map shows the location of Iowa’s trout fishing streams located in northeast Iowa. A direct comparison of karst topographic areas.