Department of Earth Science |Northeastern Illinois University

ESCI 337
Fall, 2005

Daily Objectives #21 (November 16, 2005)                                        Dr. Sanders

By the end of today's class, you should be able to do the following:

v  Sketch hydrogeologic cross sections that illustrate the following:

   unconfined aquifer
   u   confined aquifer
         u   water table
   u   potentiometric surface
   u   hydrostratigraphic units that do not completely coincide with lithostratigraphic units
   u   no-flow boundary
   u   constant head boundary

  Use published maps to investigate geologic conditions in this area:  Dupage County, area bordered on the east by Salt Creek, on the south by Spring Brook, and on the west by Meacham Creek.  (This is in the approximate area of Itasca.)  Use the following resources, plus any others you can find:

    p 7.5 minute topographic quadrangles [Note: Identify the area by County, Township, Range, and Sections, and tell what topo quads cover it.]
    p Summary of the Geology of the Chicago Area, by H.B. Willman (1971)
    p Quaternary Deposits of Illinois, by Jerry Lineback and others (1979) [This map is hanging in the classroom.]
    p Geologic Map of Illinois, by H.B. Willman and others (1967)  [This map is hanging in the classroom.]
    p Stack-Unit Mapping of Geologic Materials in Illinois to a Depth of 15 Meters, by Richard C. Berg and John P. Kempton (1988)
    p Glacial Drift in Illinois: Thickness and Character, by Kemal Piskin and Robert E. Bergstrom (1975)
    p Buried Bedrock Surface of Illinois, by Beverly Herzong and others (1994).  [Compare this to the preceding map.]
    p Potential for Contamination of Shallow Aquifers in Illinois, by Richard Berg and others, 1984.

v  Write a description of the geology of the area.

v  Use the ISGS's online database of well and boring data.   Access this by going to the Earth Science Department home page , then clicking "Links to More Earth Science Sites", then clicking the link to the ISGS, then "Online Well Data".  Click on "Database Query".  (The first time you do this, you probably will have to first install the Jinitiator plug in, as described on the website.)  Enter search criteria, then click "Execute Search".  When the search is done, you will get a message saying how many well records there are, and you can then click through them by using the tabs at the bottom of the database window.  HINT:  Look for records that have a complete "Driller's Log"!

v  Complete Homework #5: With two classmates, using topographic information and boring log data, construct three cross sections showing the geology of the project area.  You must work together, but each group member should take primary responsibility for one of the three cross sections.

Select boring logs and locations that are most useful to you.  This means that the borings are in good locations, and it also means that the logs themselves are useful! Not every log is a good log, so make your selections carefully. 

Make your cross section run in a crooked line that extends from boring to boring, rather than trying to make a straight line.  Use a vertical exaggeration of 100x--in other words, your vertical scale should be 100 times your horizontal scale.  The horizontal scale should equal the scale on the topographic map: 1:24,000.

After reviewing the locations of useful boring logs, within each group, decide where to draw three lines of cross section.  You might want to get a rough idea of the subsurface geology before you determine exactly where the cross sections will be placed.  Remember, the goal here is to delineate the boundaries (constant head, no-flow, or water table boundaries) of a hydrogeologic system, so let the geology of the system be your guide as you determine where to draw your cross sections.

Draw your cross section in pencil!  You will have to make changes, so consider this a draft.  (Eventually, after you have worked out all the problems, and just before you hand in the final product at the end of the semester, you will go over your pencil lines in ink--but this is a few weeks off!)  Please cooperate with your group members to give all of your cross sections a similar format.

Be sure to include the horizontal and vertical scales, show the position of each boring that you used to plot the cross section (label it with the final 5 digits of the well's API number), label any major geographic features such as rivers/lakes, highways, and so on, and give the cross section a title.  Make sure your name is on it, in small letters in an inconspicuous place. 

What to Hand In:  Hand in the cross sections together as a group.  In addition, each group should provide a single copy of the topographic map showing the lines of the cross section.
Department of Earth Science | Northeastern Illinois University

© 2005 Laura L. Sanders.  Last updated November 16, 2005.