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Glaciers-Iowa
by Ryan Fitzpatrick
Physical Geology
Fall 2007
         

Glacial Features of Iowa

                                                 

 

     When you think of the state Iowa, most people think of a state that is cover with fields of corn and soybean.  The reason why the state has such good soil to grow such large amounts of corn and soybeans is because of the geology of the state.  The state is a highly glaciated landscape.  The region of the upper Midwest went through four periods of glaciation, they are in order of oldest to youngest, Nebraskan period, Kansasan period, the Illinoian period and the Wisconsinan period.  The Nebraskan period and the Kansasan period are so old they are hard to distinguish the differences so they call the formations in these zones part of the Pre-Illinoian period as can be seen in Figure 1.
 

  

Figure 1:  Areas of Glaciations in upper mid west United States.
 

     Within the state of Iowa you can easily the area in which the glacier was on this area is the Des Moines lobe.  The areas of the Iowan Surface, the Southern Iowa Drift Plain and the Northwest Iowa Plain are area of glacial outwash (Figure 2).  The land form known as the Paleozoic Plateau is an area that was not affected by any of the glaciated periods and is mostly an area with a lot of exposed bed rock.  The area is famous for effigy mounds and the Ice caves in the town of Decorah, Iowa (Figure 2).

 

 Figure 2: Landform Regions of Iowa
 

      As we know glaciers advance and retreat, with the Des Moines we are able to see these advances such as the Bemis advance, the Renwick advance, the Algona advance and the Altamont advance.  We are able to see these advances within the landscape with the formation of hilly areas known as moraines (Figure 3).  The most well known moraine know to Iowans is the most southern point of the Bemis Moraine because this is the point in which the state capitol building is on (Figure 4).  Most of the moraines and advances are named for towns that lye on those moraines.  

  
Figure 3: Advances of the Des Moines Lobe

 

Figure 4: Iowa State Capitol Building in Des Moines, Iowa.

 

     Glaciers, as we know, move and pick rocks and soils if it pick up those thing it has to put them.  The formations that we can see with in a landscape that come from the glacier depositing soil are Kames and Eskers.  An esker is a sand bar that was within the glacier and was deposited when the glacier was done melting, an example of an esker can be seen below in figure 5.  The other feature that is propionate is called a kame.  A kame is where a glacier deposits all of the soil, rocks and tilt in a mound formation, and example of a kame is the Ocheyedan Mound in the town of Ocheyedan (figure 6).  Kames are part of a landscape known as a knob and kettle landscape.  The kames are the knobs and locations in which large chunks or ice stood after the glacier melted form indents in the landscape we call these kettles since they are like large pots.  An example of a Kettle is the Freda Haffner Kettlehole (figure 7) in Dickenson County.  Dickenson County is a county that also has glacial lakes which is visible by the presence Spirit and Okoboji lake systems.
 

 

Figure 5: Example of esker.

 


Figure 6: Ocheyedan Mound    

    
                                                                                                                             

Figure 7: Freda Haffner Kettlehole
 

     Iowa’s glacier has hidden a great impact feature known as the Manson impact crater.  You are unable to tell at the surface there is a crater there the way it was found to be a crater is by an analyst of the watershed.  The loess hills of western Iowa are known as the second deepest in the world, comparable to those in china.  Loess is a wind derived soil found on the opposite side of a river valley that the winds come in.  The loess in western Iowa was blown on top of the glacier and then was deposited top on the glacial tilt as the ice melted.
 

               
 

Figure 8: Map of Loess Thickness in the mid west.     

      

Figure 9: Profile of Loess

 

 

Figure 10: Diagram how loess was deposited in Western Iowa.

 

The features pointed out are the largest and most noticeable features because or effected by glacial geology.  If you have the time go and explore and find the smaller features that affect your everyday life.
 

Works Cited

Burras, Dr. Lee. Lectures and notes from Iowa State University courses EnSci 473I, EnSci 402 and Agron 260.  2004-2006.  Ames, IA.

Photo Credits

Figure 1. Iowa DNR.  www.igsb.uiowa.edu/Browse/glatrail/glatrail.htm

Figure 2. Iowa DNR.  http://www.igsb.uiowa.edu/Browse/geoiowa/GEOIOWA.HTM .

Figure 3. Iowa DNR.  www.igsb.uiowa.edu/Browse/glatrail/glatrail.htm

Figure 4. Wikipedia.  http://en.wikipedia.org/wiki/State_legislature_(United_States)

Figure 5. Iowa State University Geographic Information Systems Support and Research Facility.  http://ortho.gis.iastate.edu

Figure 6. Iowa DNR.  www.igsb.uiowa.edu/Browse/glatrail/glatrail.htm

Figure 7. Iowa DNR.  www.igsb.uiowa.edu/Browse/glatrail/glatrail.htm

Figure 8.  USGS. Ritter, Michael E.  The Physical Environment: an Introduction to Physical Geography.2006. 11-11-07.  www.uwsp.edu/.../eolian_systems/loess.html

Figure 9. Harrison County Conservation Board website.  www.harrisoncountyparks.org/loesshills.htm

Figure 10. USGS.  http://pubs.usgs.gov/info/loess/

Background

I have my B.S. in Environmental Science from Iowa State University in Ames, IA.