TENNESSEE DIVISION OF GEOLOGY MAPPING IN THE VALLEY AND RIDGE PROVINCE: AN UPDATE

During the past three years, Tennessee Division of Geology personnel have completed five geologic quadrangle maps, the Binfield, Camelot, Mascot, Mosheim, and Newport quadrangles, using Arcview( 3.2 software. Work was partially funded by the U.S. Geological Survey StateMap program. More than one mapping and compilation methodology has been used on several of the projects; for example, two authors prepared the Camelot quadrangle using paper maps and field books, working in separate parts of the map defined by geologic contacts. To compile the field data, one used "event themes" in Arcview, driven from a single spreadsheet. Each written field observation is normalized to a point with attributes such as bedding strike and dip, lithology, joint strike and dip, fold attributes, formation, etc. This relational database structure facilitates later queries, for example to plot all records of vertically dipping limestone beds in the Knox Group. The other author used separate themes for field data, for instance, a point theme for bedding attitudes, another for fold axes, and a line theme for each lithology to show outcrop locations coded by color. This approach made for quicker, more direct editing and interpretation in the office, and a data printout similar to colored pencil compilations on mylar, but created a more cumbersome file structure. Themes for line features (contacts and faults) and polygons (bedrock units) were done separately by the two authors to allow simultaneous editing, then combined on the final map.

For the Binfield quadrangle, field data were compiled by one author again using many separate themes, and the other using "event themes" from a single data table; in this instance, field observations input into a Trimble( Geo-Explorer 3 GPS unit. The Newport quadrangle was done by adding GPS data and field note data, both in separate spreadsheets, and both using "event themes." In each instance, Arcview GIS software provided enough flexibility to combine these formats and produce a geologic map.

Noteworthy features are often encountered in the course of mapping, and it may be desirable to include these observations without the requirement of a comprehensive report. If a digital product is released, additional data can be incorporated in Arcview or as separate files to give substantial latitude as to what can be presented.