Field Geophysics public home page, Fall 2022
Field geophysics uses physical principles to learn about the structure
of the earth through measurements made by students. We will make several excursions near Boulder for our field projects. COVID-19 will probably prevent us from our usual excursion to the vicinity of the Caribou Mine above Nederland for gravity and magnetics, but we'll leave open the possibility, depending on circumstances. 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 we'll return to Caribou for the first time in ages for all of our field experiments.
Course material will be on Canvas (canvas.colorado.edu) during the term. The calendar on that site will be updated before this one.
This site is to provide a public interface for class materials that might be useful to others.
Meeting Time: Nominally T-Th 12:30 pm, but see below .
The provisional 2022 schedule is here for reference (the Canvas site will be the active site for the class). Note that this course is very front loaded: we do a lot in the first few weeks, so things are very busy into early October. Even when it does appear, 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).
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. You will want to take note of the errata page. Milsom's Field Geophysics is a handy
field reference. We will be using the software from this
in this class. If you are using your own copy, please be sure to update the software as necessary from the updates page. (2015 release should be up to date; in any event, the new software (v2.0 and up) has an internal update mechanism and no longer requires downloading an updater).
Course Information Online (some of this might be dated)
Field how-tos:
Instructor: Prof.
Craig Jones, Benson Earth Sciences 440C
TA: none 2022
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 10.4-10.9 at least. 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).
- 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.
- 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. Rather like using a cannon to kill gnats, though.
- 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, doesn't come cheap.
- 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 is commercial plotting and analysis software for Mac only. It is unique in supporting a number of earth science plotting styles like spidergrams, strat plots, and stereonets. It also has a large statistical package. It is 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 Saturday, August 20, 2022 1:04 PM
