GIS Tools for 3-D Surficial Mapping in Ohio

Abstract

The Ohio Department of Natural Resources, Division of Geological Survey is currently mapping the surficial geology of Ohio in three dimensions (3-D) using a modified version of the stack-mapping technique of Kempton (1981). The stack-mapping technique depicts the geology for an area in 3-D by listing the unconsolidated (mostly glacial) geologic units from the surface to bedrock, the thickness of each unit, and the underlying bedrock unit. The new mapping of the surficial geology is intended to replace the older and smaller-scale mapping that was based upon generalized, two-dimensional mapping techniques. Three ArcMap-based software applications were developed to assist with the stack-unit mapping program. The first software application used the lithologies from water wells to create on-screen graphics representing the stratigraphic columns for each well record. These stratigraphic columns are interpreted by the geologist to assign a generalized stack unit for each polygon. The second software application consists of two tools used to attribute and label the stack-map polygons, which will capture the information in the GIS and for cartographic display. The first tool attributes a one-to-many relationship between a surficial-geology polygon and the lithology table. The second tool labels the surficial-geology polygons with the stack text for use in map publishing. The third application performs custom queries against the lithology table that can be used to create derivative mapping products, such as location and thickness of sand and gravel resources. These three applications allow the efficient creation of 3-D surficial-geology polygons and labels within a GIS database, and provide analysis tool to facilitate the use of the 3-D surficial geology maps for specific applications.