Field Geophysics public home page, Fall 2024
Field geophysics uses physical principles to learn about the structure
of the earth through measurements made by students. Our goals are to learn the basics of the techniques,
what kinds of targets they are good for, how to make field measurements and
make simple reductions in the field to see if measurements are likely good,
how to interpret the field measurements, and finally how to take advantage
of the complementary nature of the different techniques. We will use seismic
refraction, reflection, electrical resistivity, ground penetrating radar, gravity,
and magnetics in the course.
In 2019 we did work on CU's South Campus land, which we built upon in 2020. In 2022 and 2023 we returned to Caribou for the first time in ages for all of our field experiments. In 2024 we'll go back to South Campus.
Course material will be on Canvas (canvas.colorado.edu) during the term. This site is to provide a public interface for class materials that might be useful to others (plus the schedule page works here but is messy to embed in Canvas)..
Meeting Time: Nominally T-Th 12:30 pm, but see below .
The 2024 schedule is here and is highly tentative (I have included all possible equipment, which would create 9 labs, which is quite high, so I expect to drop one or two techniques, depending on class interest and instrument availability (the Canvas site will be the active site for the class otherwise). This course is usually very front loaded, but we lose 3 full classes in September for various reasons, so this will stretch into November. The schedule is likely to change so check back frequently. You are expected to have read and understood the reading prior to the lecture/lab where they are listed--there are reading quizzes on lecture days when reading is assigned.
Meeting Place:
- Labs: mainly loading dock. Exceptions as noted.
- Labs: BESC1B75 or BESC 385 (computer lab) unless otherwise specified.
GEOL4714 is for undergraduate credit.
GEOL5714
is for graduate credit. Usually 5714 is the same as 4714 but the student must
complete a field final as well (this is gathering and interpreting data in
a single afternoon of the student's choice at a specific field site announced
to the student ahead of time).
With the high enrollment in 2024 in 5714, there will probably be two groups for field finals.
Course goals:
- Prepare clear and complete notes on field measurements
- Prepare clear, neat and complete reports on analysis of field data
- Explain the relationship between field measurements and the relevant physical properties of the subsurface
- Knowing the approximate values of physical parameters of common shallow-earth materials
- Construct a deployment of different types of geophysical equipment appropriate for the target to be studied
- Recognize potential complications to field measurements and develop means of minimizing said complications
- Construct a model of the subsurface consistent with field measurements
- Articulate (or better, define) the tradeoffs present in interpreting different geophysical measurements.
- Develop a plan for attacking a geophysical target that can include multiple techniques
Reading:
Readings, including some class handouts, are listed on the schedule page. Textbook is Burger, Sheehan and Jones's Introduction to Applied Geophysics: Exploring the Shallow Subsurface, now published by Cambridge Univ Press, but the Norton version is identical. You will want to take note of the errata page. We are making a new edition of the text and so might share some of the revised text with the class. Milsom's Field Geophysics is a handy
field reference. We will be using the software from the Burger text
in this class.; this can now be downloaded from the new publisher (Cambridge).; if I make updates to the software, there will be a local site for the revisions.
Material below is not regularly updated (current versions should be on Canvas)
Course Information Online (some of this might be dated; more recent material in Canvas)
Field how-tos:
Instructor: Prof.
Craig Jones, Benson Earth Sciences 440C
TA: TBD
Course goals:
After completing this course, students should be able to
- Prepare clear and complete notes on field measurements
- Prepare clear, neat and complete reports on analysis of field data
- Explain the relationship between field measurements and the relevant physical properties of the subsurface
- Knowing the approximate values of physical parameters of common shallow-earth materials
- Devise and conduct a deployment of different types of geophysical equipment appropriate for the target to be studied
- Recognize potential complications to field measurements and develop means of minimizing said complications
- Construct a model of the subsurface consistent with field measurements
- Articulate (or better, define) the tradeoffs present in interpreting different geophysical measurements.
- Develop a plan for attacking a geophysical target that can include multiple techniques
Software ideas:
From time to time you might want to make plots in something other than the software with the text. Most commonly, these would be scatter plots. Note that CU has site licenses and discounts for many software packages. Here are some options for you to consider, roughly in order of increasing cost:
- gnuplot is copyrighted but open source script-driven software that can be installed on most operating systems.
- Grapher (Mac only) is a utility Apple has shipped with Macs for awhile, usually in the Utilities folder within Applications. It has the ability to generate scatter plots (kind of hidden--choose New Point Set under Equations for a default 2-D plot). Free with Mac OS since 10.4. Can also be used as an equation editor.
- Numbers, the spreadsheet app within Apple's iWork suite, also will allow creation of scatter plots. iWork is free on campus computers but would still need to buy on personal Macs (can get in the AppStore).
- GMT (generic mapping tools) is a set of Unix commands to assemble postscript graphics files (somewhat like gnuplot). Although the majority of the commands are map-based, there is psxy, which can generate scatter plots. A GUI front end for GMT called iGMT is available for download. Both are free and can be installed on most computer systems (most easily through things like fink). While GMT is very much a widely used tool, iGMT appears to be falling behind.
- Plots in Excel can be ugly and difficult to customize, but most students have Excel. A tutorial can help.
- OriginPro is Windows software for plotting and is now available on a campus site license.
- JMP is primarily a statistical analysis package for both Windows and Mac, but does have some other tools that could be useful. There is currently a campus site license for JMP Pro.
- Kaleidagraph is commercial plotting software for Mac and Windows that is far more flexible than Excel and fairly intuitive. There is a demo version and an academic rate.
- DeltaGraph is a fairly old and venerable commercial charting and graphing program for Mac and Windows. There is an academic discount. I have not used this for years, but it is an option. Appears they have yet to release a 64-bit version for modern Mac OSes.
- IDL is similar to Matlab but was developed at CU and so we have a great site license program. However, the focus of this software is involved visualizations, so not the easiest way to make a plot.
- Matlab can make scatter plots (and lots of other things) on Macs, Windows, and Unix machines through text commands (though some GUI interfaces can be used in some instances). CU has a site license and there is a student edition of Matlab available. While like using a cannon to kill gnats, there are times it is a lot handier for some things we do (e.g., contour plots).
- Mathematica similarly is using a sledgehammer to put a marshmallow into a square hole, but it is also available through a campus site license.
- Grapher is Golden Software's venerable plotting package for Windows.
- SigmaPlot is another venerable plotting package for Windows that, like Grapher, didn't come cheap. It sounds like this software is being moved to a cloud-based operation.
- Igor Pro is a commercial scientific plotting package for Mac and Windows. Although there is an academic discount, it isn't particularly cheap. There are many scientists who rely on this.
- Aabel was a commercial plotting and analysis software for Mac only that apparently has bitten the dust. It was unique in supporting a number of earth science plotting styles like spidergrams, strat plots, and stereonets. It also had a large statistical package. It was not cheap, even with academic discounts.
Other resources:
Older stuff of interest
The Caribou Park area was the site of an illegal offroad rally 9/23/00; I've
put some photos from 1998 and 2000 together
on a special Mudfest page for your amusement.
Please send mail if
you encounter any problems or have suggestions.
C. H. Jones | CIRES | Dept. of Geological Sciences | Univ. of Colorado at Boulder
Last modified at Tuesday, August 20, 2024 1:42 PM