Department of Earth Science |Northeastern Illinois University
Daily Objectives #15 (October 18, 2007)                                        Dr. Sanders

 By the end of today's class, you should be able to do the following: v Hydrostratigraphy and Flow Systems List the four different kinds of flow system boundaries and sketch cross sections or maps showing examples of each. v Hydrogeologic Maps and Cross Sections Find borehole data for a given area in Illinois, and use it to delineate flow system boundaries, identify hydrostratigraphic units, and construct hydrogeologic cross sections.

Today's Agenda:

v Hydrostratigraphy and Flow Systems
• Describe how to delineate hydrostratigraphic units when they involve two (or more) lithostratigraphic units, or when they involve only a portion of a lithostratigraphic unit.
• List the four different kinds of flow system boundaries.  For each one, give an example of how this kind of boundary might occur in a hydrogeologic setting.  Draw a sketch of each example.
v Hydrogeologic Maps and Cross Sections (Homework #4!)
• Explore the questions, issues, and difficulties that commonly arise in constructing hydrogeologic cross sections.
• Gather data on the subsurface conditions of the study area described in class (the village's name will be given in class).  Construct a cross section for the area.
• Coordinates of the Community Water Supply (CWS) wells for the village are as follows:
 CWS # LONGITUDE LATITUDE (decimal degrees) 00404 -88.16533 39.25964 47782 -88.17356 39.25601 47783 -88.16998 39.25866

Your job is to collect subsurface data and create cross section(s) that portray the geologic setting of these water supply wells.  Your cross section should illustrate the hydrogeologic system--that is, it should have boundaries.  Keep that in mind as you decide how far your cross section should extend.

The cross section will extend from point to point, not necessarily in a straight line (some call this a "fence diagram".)
Use as many points as you need to represent the system.

On your cross section, show the following:
• Elevation scales (one on each side of the drawing)
• Horizontal scale (a graphical bar scale)
• Statement of vertical exaggeration (for example, "Vertical Exaggeration = x25", or "Vertical Exaggeration = 50:1")
• Letters designating the line along which the cross section is drawn--for example, A-A', or B-B'.
• Single black lines outlining lithostratigraphic and/or hydrostratigraphic units (do not fill the area with a pattern)
• A label for each geologic unit portrayed.  If you know the formal formation name, give it; otherwise, use a label such as "Clay", "Sand", etc.
• A label for any significant local features, especially lakes or streams.
• A single black line showing the location and depth of each well that appears on cross section; at the top, give the five-digit unique number code for that well (digits six through ten of the "API number").
• Total depth of each well that appears on the cross section (print "TD = __" at the bottom of each well).
• Ideally, the cross section should fit on one sheet of 11" x17" paper (or smaller).
• On a separate sheet, give a map showing the line of cross section.  Be sure to include the "A-A' " or "B-B' " designation on it.
Draw your cross section IN PENCIL!!!!  (You probably will have to change it after it is reviewed.)

You may find it helpful to use www.topozone.com to locate the CWS wells.  Also, check out earth.google.com .

We will be working on this project today and Tuesday.  By the end of the day on Tuesday, you should have delineated the boundaries of the flow system, collected all the boring log data you need, identified the hydrostratigraphic units, and sketched out what you think the final cross section will look like.  You also may wish to get a start on the final drawing.

Please cooperate with each other to collect data and analyze the problem; each person should hand in his or her own cross section.

Department of Earth Science | Northeastern Illinois University

© 2007 Laura L. Sanders.  Last updated October 18, 2007.