of Earth Science |Northeastern
Daily Objectives #21 (November
By the end of today's class, you
be able to do the following:
v Sketch hydrogeologic cross
sections that illustrate the following:
u confined aquifer
units that do not completely coincide with lithostratigraphic units
u no-flow boundary
v 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
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
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
be 100 times your horizontal scale. The horizontal scale should
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
of each boring that you used to plot the cross section (label it with
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
a title. Make sure your name is on it, in small letters in an
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.
of Earth Science | Northeastern
© 2005 Laura L.
Last updated November 16, 2005.