Kansas Geological Survey, Open-file Report 2000-65
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Two objectives were involved in this task of two-dimensional mapping: (1) continue high-resolution mapping of the alluvial landscape; (2) refine the soils map of the installation to render soils-geomorphic mapping in a realistic fashion; (3) digitize the drainage system of the entire installation with field verification using high-resolution GPS; (4) continue mapping the loess distribution; and (5) map the other discrete landforms of the installation.
Procedures employed included (1) mapping alluvial landforms using stereoscopic coverage of black and white aerial photography; (2) foot survey of each accessible valley in order to refine the reconnaissance maps, (3) a second foot survey of each valley from the channel bed or water's side to correlate fills exposed in channel banks with their overlying surfaces, and to search for exposed sections worthy of documentation and, in some instances, radiocarbon dating; and (4) exploration of the unexposed valley fills using motorized, trailer-mounted coring machines with a 25-m maximum reach, and using hand augering and coring devices.
Exiting available digitized soils data for the base are of poor quality due to mismapping in the field and to imprecise electronic rendering. The Natural Resources and Conservation Service (NRCS) electronic soils maps, available from Data Access and Support Center (DASC), Kansas Geological Survey are, unfortunately, of average to poor quality for Fort Riley: in an attempt to combine different soil phases into a single soil series, the developers of the electronic database have often crossed series and grouped unrelated soils into associations. As a result, the soils map exhibits some unusual and unnatural patterns. Hence, a great deal of project time was used to make correction and modifications to the soils map through field checking and remapping and to modification of existing electronic files. The importance of doing this was that much of the mapping of landforms and deposits is dependent upon accurate soils mapping, i.e., soils-geomorphic mapping.
Another time-consuming but necessary activity was that of developing an accurate and realistic electronic rendering of the drainage system of the base. This was necessary for the accurate mapping of the alluvial units. Existing large-scale maps available from the installation are of relatively high quality but have become dated due to stream channel and landscape modification and to natural processes such as channel meandering and avulsing. Adjustments and refinements of the drainage system were carried out through (1) digitization of the stream network for the entire base; and (2) field checking and ground-truthing of selected stream segments and confluences using high-resolution GPS (Trimble system). Additionally, some GPS assistance was provided by installation personnel. The final product is a detailed digital elevation model of the installation.
Because of the size and restricted access to much of the installation, loess distribution was initially mapped using the updated soils map for the installation. After mapping the older loesses (the Loveland and Peoria loesses), the Distribution of the Bignell loess was determined because of its importance in the preservation of the archaeological record. The distribution of the Bignell loess was determined through coring, trenching, and topographic interpretation, whereas the electronic map was relied upon for distribution of the Peoria and Loveland loesses.
Because other landform units exist on the installation and exhibit archaeological importance, they were mapping using both aerial photography and field survey. Other landform units mapped are colluvium, or slope deposits; alluvial fans, which merge into the valley terrace and flood plain fill; and bedrock outcrops. Bedrock areas included vertical and near-vertical non-alluvial landscapes and tracts where no significant loess covering exits, only a shallow surficial soil.
It was not possible to conduct this particular task due to a lack of dig permit data records. This was due to the fact that the government was unable during the contract period to provide the principle investigator with the paper hardcopy records as specified in item 4 of the statement of work in the schedule of supplies/service.
Subsurface alluvial stratigraphic data collected during the course of previous investigations and two dimensional mapping of the alluvial surfaces was used to develop 3-D visualizations of the valley bottom topography on the installation. In accordance with the contract, ESRI ArcView 3-D Analyst software was employed to render these views of the valley fills. The objective in providing this perspective is one of illustrating the range in topography and the implicit range in ages and the depth to which cultural materials may be buried and thereby exposed to disturbance by military training. Other software and databases were used to generate three-dimensional, low-oblique perspectives on the study basins.
This document represents the first draft report of research outlined under this contract. Five copies of the final report shall be submitted with an accompanying Iomega-brand Zip disk containing all text, data and ESRI software (ArcView/ArciNFO) project files.
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Kansas Geological Survey
Placed online March 7, 2012; originally released June 2000
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