Geology 102 - Environmental Geology

Spring, 2002 - Lab # 1

Geological Information Sources

Most geological knowledge is applied in a spatial context. Thus, in order to consider the implications of geologic processes on humans or humans on their geologic environment, you must define that context. The tools which we use are aerial photographs, maps, and site-specific documents.

I) Aerial photographs are the base source of information for all modern maps. Sophisticated plotters generate topography from the parallax, or apparent difference in spacing with differing elevation, of aerial photographs. Vegetation, streams, and human artifacts such as buildings and roads are interpreted from the photos. It is important to realize that even a detailed topographic map is an interpretation of reality, not reality itself. Microsoft's TerraServer Web page provides aerial views of much of the contiguous 48 states - for a small, low-resolution example, see Bozeman.  Aerial photographs are available for purchase for most of the country from the UDSA Farm Service Agency Aerial Photography Field Office, 2222 W 2300 S, P. O. Box 30010, Salt Lake City, UT 84130-0010 - (801) 975-3503. They are ordered by location, season, wavelength (visible or IR), B&W or color, and size (up to 38" square!).

II) Topographic maps are the fundamental tool for location. They are produced at various scales, although large-scale maps such as 1:24,000 and medium scales like 1:250,000 are the most common and useful. The green vegetation overlay (including variants for swamps, orchards...) is also common and useful. Consider the sample topographic quadrangles and the symbol page and visualize the real topography! They can be found in Renne Library (western U.S. only) and can be purchased in local stores (selected areas only), at the Montana Bureau of Mines and Geology (MBMG) at Montana Tech in Butte (all of Montana), or from the US Geological Survey (USGS) Regional Mapping Offices.  They are also available as CD-ROMs with analytical capability (as from Topo.com and DeLorme) and on-line from Topozone.com and some states. (e.g., Montana).

III) Geologists use the topographic maps as a base on which to display geological characteristics (geologic maps). The most common characteristics are the type of bedrock, the age of bedrock, and features implying deformation, such as tilts, folds, and faults. Less commonly, surficial deposits like stream alluvium, lake beds, and glacial till may be shown. Other uses of topographic base maps include floodplain maps, groundwater maps, thickness-of-sediment maps, and suitability maps. Look at the examples, and recognize that only in a few places in the country has the detailed fieldwork to make these maps been done! They can be used in Renne Library and purchased from MBMG or the USGS.

IV) Many sites of geological interest, from landmarks like the Grand Canyon to hazards like flash floods to waste disposal facilities, have been examined and written about in detail. Such writings may be documents from government agencies like the United States Geological Survey Professional Papers or the Environmental Protection Agency to formal publication in technical journals such as the Geological Society of America Bulletin to informal publication in Sierra, National Geographic, or New Republic. These sources can be accessed through on-line indexes such as Expanded Academic or GEOREF. As with most keyword searches, however, there is a fair amount of skill/art/luck in the process!

V) EXERCISE

A) Split into groups of two to four.

B) Take a set of latitude/longitude coordinates from the lab instructor (see bottom of page) and find out what the site is, what the geology of the site is, and what has been written about the site. Think of this as a scientific scavenger hunt! First group done may get a (trivial) prize!

1. Use Topozone to find a large scale (small area) topographic map of your site.  What is it?  Ask your instructor if you are not certain.  What is the name of the detailed (1:24,000) map quadrangle in which your site is found? [NOTE:  Terraserver's Advanced Search capability will find the location, but doesn't appear to yield the quadrangle name.]
2. Once you have located the site, split your group into two parts. One will look for geologic map resources, the other will search for text references.
3. Go to the MSU Map Library in Renne Library (Reference) and  use the state topographic map indexes (western US only) to try to find a paper copy of the topographic map you found.  In the Map Library, use the state geologic map indexes and the Index to USGS Publications to locate geologic map resources.  Make note of your successes (map source and title) and failures (not published, published but not in Renne, other). Return to the lab room and summarize briefly the topographic and geologic setting of your site.
4. From the Renne Library on-line indexes, search the Government Documents Index (in Physical Sciences) to find agency publications, one of the general periodical indexes (such as Expanded Academic) to find nontechnical publications and GEOREF (in Geology) to find technical publications.  Make sure that your keywords are well-chosen! Print the summary or Abstract of the best (most complete) publication you can find on the topic of interest. See if you can find the publication! [Library construction may make this impossible.]  Leave the resources where you found them! Return to the lab room.
5. Reassemble at the lab room as soon as possible, but in all cases with at least 30 minutes left in the lab. We will discuss the results of your searches briefly as a lab wrap-up.