Geologic Information Sources

GOALS:

• To develop some ablitiy to seek out and find map information from a variety of sources.
• Learn a little about the type of geologic information that is "out there."
• Have some fun and familarize ourselves with the library resources.

INTRODUCTION

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 space. Aerial photographs, maps, and site-specific documents are all tools which can provide information regarding an area. Below there is a short discussion of these types of tools. Read through that first before starting on the exercise.

I) Aerial photographs are the basis 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. Let's look at an example. 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 Off! ice , 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, which we examined last week, 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. 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!

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 (what kind of rock you see there) 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!

Scavenger Hunt List:

1. Name of topographic map quadrange in which your site is found. Use Topozone to find a large scale (small area) topographic map of your site. [NOTE:  Terraserver 's Advanced Search capability will find the location, but doesn't appear to yield the quadrangle name.]
   {HINT} Once you have located the site, split your group into two parts. One half will look for geologic map resources, the other half will search for text references.
2. Geologic map resource. Go to the MSU Map Library in Renne Library (Reference). 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). Summarize briefly the topographic (is it steep, flat, are there rivers, etc.) and geologic setting (what kind of rock do you see, is there faults, etc.) of your site and return to the lab with a reference to your geologic map and summary.
3. Text References. From the Renne Library on-line indexes , search the Government Documents Index (in Physical Sciences ) to find one agency publication. Make a note of the agency and publication. From one of the general periodical indexes (such as Expanded Academic ) to find one nontechnical publication. Again, make a note of the publication and what index you found it in. Finally use GEOREF (in Geology ) to find one technical publication. Make a note of that publication and where it is found in the library (either on-line or in the stacks).

Reassemble at the lab room as soon as possible, but in all cases with at least 20 minutes left in the lab. We will discuss the results of your searches briefly, hand out the prize for first place and as a lab wrap-up.