of Earth Science |Northeastern
Objectives #15 (October 18,
the end of today's class, you
should be able to do the following:
and Flow Systems
Maps and Cross Sections
the four different kinds of flow system boundaries and sketch cross
sections or maps showing examples of each.
borehole data for a given area in Illinois, and use it to delineate
flow system boundaries, identify hydrostratigraphic
units, and construct hydrogeologic cross sections.
and Flow Systems
Maps and Cross Sections (Homework #4!)
how to delineate hydrostratigraphic
units when they involve two (or more) lithostratigraphic
units, or when they involve only a portion of a lithostratigraphic
- 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.
the questions, issues, and difficulties that commonly arise in
constructing hydrogeologic cross sections.
data on the subsurface conditions of the study area described in class
(the village's name will be given in class). Construct
cross section for the area.
of the Community Water Supply (CWS) wells for the village are as
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:
Draw your cross
section IN PENCIL!!!! (You
probably will have to change it after it is reviewed.)
scales (one on each side of the drawing)
scale (a graphical bar scale)
of vertical exaggeration (for example, "Vertical Exaggeration = x25",
or "Vertical Exaggeration = 50:1")
designating the line along which the cross section is drawn--for
example, A-A', or B-B'.
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",
- 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").
depth of each well that appears on the cross section (print "TD = __"
at the bottom of each well).
the cross section should fit on one sheet of 11" x17" paper (or
- 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.
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.
© 2007 Laura L.
Last updated October 18, 2007.