Field Geology 2009: |
 Photo by J.S. Aber; Photo date January 30, 2009 |
Field Geology 2009: |
Photo by J.S. Aber; Photo date January 30, 2009 |
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Chase County is situated in the Flint Hills physiographic province in eastern Kansas. Physiographic provinces categorize Kansas by overall landscape, vegetation, and physical geology. The Flint Hills are gently rolling hills, covered in a tallgrass prairie, that separate the oldest from the youngest rocks in Kansas. General physical geology of the state is shown on a map from the Kansas Geological Survey (Figure 1-right click on the image and see the larger version by chooosing to open in a new window or tab). Chase County is marked with a star. A geologic map displays bedrock formations on or near to the surface of Earth by geologic age as if all human-made structures, natural soils and plants were invisible. The horizontal distribution of rocks is layered over a map distinguishing county political boundaries and the geologic age in shown in the legend on the left. To envision what the rock formations look like below the surface a vertical slice, called a geologic cross section, is shown below the map. This portion of Kansas geology is taken from a line labeled A-A' that crosses Kansas in an east-west direction, approximately following the Interstate 70 roadway.
In this generalized map, Chase county is covered in a pale blue color, which stands for Permian age rock over 299 million years old. In the geologic cross section, this blue color shows that a thick sequence of rocks was deposited in the Permian. Assuming the rock layers were horizontal at the time of deposition, the cross section shows that they were subsequently tilted and dip gently to the west. |
 Figure 1. Generalized geologic map of Kansas. Chase County marked with a star. Image taken from Kansas Geological Survey www.kgs.ku.edu/General/geolSheetMap.html |
 Image taken from Kansas Geological Survey but no longer found online. See updated map at www.kgs.ku.edu/General/Geology/state23.html | The geologic past of any region may be interpreted from the type of rocks, fossils, and minerals present. While the general geology map provides a time frame for Chase county bedrock, greater detail is needed. A Kansas geologic map taken from the Kansas Geological Survey with more detail is shown in Figure 2 (right click on the image and see the larger version by chooosing to open in a new window or tab). Here the Permian System is subdivided into groups and Chase county has rocks from the Council Grove and Chase Groups. These groups are comprised of limestone and shale that alternate in rock layers that are stacked in succession and referred to as layer-cake stratigraphy. Additionally, many of these limestones are all used as building stones in the state of Kansas and beyond. |
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The rock layers of groups are further subdivided in geologic time as shown by this detailed geologic map of Chase county (see Figure 3 - right click on the image and see the larger version geologic map of the county that is detailed and up-to-date; chooose to open in a new window or tab).
For the rocks in Chase county, these rock layers are subdivided into formations and members, which are described at a Kanasas Geologic Survey publication, Stratigraphic Succession in Kansas, edited by Doris Zeller (1968), now online at www.kgs.ku.edu/Publications/Bulletins/189/08_perm.html. Limestones are rich with marine fossils and the rocks layered in sequence during the Permian show Chase county was covered by a shallow sea that experienced changes in sea level, which created a transgression and regression of the sea many times. Kansas is geologically famous for these past repeating environments of deposition, referred to as cyclothems, which were defined by a famous Kansas geologist, R.C. Moore (1964). A cyclothem is defined by a triad of three sedimentary rocks, limestone-shale-limestone. This repeating pattern of rock represents the sea transgressing and regressing over the surface of Earth, which is a result of worldwide change in sea level. The Council Grove Group has over 300 feet of limestones and bright green, red, and gray shales. Some of the rocks in this group include the Cottonwood Limestone, Florena Shale, and Morrill Limestone members of the Beattie Formation, which lies above the Eskridge Shale. The Chase County Group is comprised of another 300 feet of limestones and bright green, red, and gray shales. Some of the limestone members of this group include the Florence Limestone, Oketa Shale, and Fort Riley Limestone members of the Barneston Formation, which lies above the Blue Springs Shale. Eskridge Shale and Beattie Formations taken together make up a minor cyclothem, which can be up to 40 feet thick. The Barneston Formation and Blue Springs Shale make up a major cyclothem, which is up to 100 feet thick. |
 Figure 3. Geologic map of Chase County, Kansas. Image taken from Kansas Geological Survey from an earlier website not available today. To see up-to-date state geology map visit www.kgs.ku.edu/General/Geology/County/abc/chase.html |
| In the county geologic map it is easy to see the tributary and main streams flowing through the county tributaries of the Cottonwood River are responsible for much of the erosion of the land surface to expose bedrock. On the map shown above, rivers are represented by the bright blue meandering lines and the white area surrounding the waterway represents river bottom alluvium or the current flood plain. The yellow color represents terrace deposits, which were former flood plains and show a general pattern of river migration to the south and southeast in this county. And so on...you modify what information fits the theme of your report! |
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I hope this gives you some good ideas for creating a report to accompany your collections. Each specimen should have an accompanying label or the metadata that goes with the sample. I have sent you a suggested template for the labels. Also, a website used in the past for GO324 Rocks and Minerals that might be of interest is www.emporia.edu/earthsci/amber/go324/collection.htm. Remember for this collection, you can include minerals and fossils.
As suggested in class, it would be best to have specimens representing the following rock member/formation in your collection from Kansas:
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These suggested rock units are shown in the figure above, which I pulled out of the larger image found at: Sawin, R. S., Franseen, E. K., West, R. R., Ludvigson, G. A., and Watney, W. L. (2008). Clarification and changes in Permian stratigraphic nomenclature in Kansas. Current Research in Earth Sciences: Kansas Geological Survey, Bulletin 254, part 2, online at www.kgs.ku.edu/Current/2008/sawin/index.html.
Finally, some links are given below for Kansas materials. Do not forget to cite and reference throughout your report. If you have any questions about good writing to avoid plagiarism, obtain the following resource: |
Return to Exploring the Flint Hills of Kansas, http://www.geospectra.net/fieldgeology/fieldgeology.htm, or GO547 Field Geology course webpage, academic.emporia.edu/aberjame/field/geology.htm.
This page is associated with Earth Science and is primarily for the use and benefit of students enrolled at Emporia State University. For more information contact the course instructor, S. W. Aber, e-mail: saber@emporia.edu Thanks for visiting! Webpage created 5 June, 2009; last update: 6 June, 2009.
copyright 2009 © Susan Ward Aber. All rights reserved.
