CREATING A SAND AND GRAVEL RESOURCES DERIVATIVE MAP FOR THE MANSFIELD 1:100,000 QUADRANGLE, OHIO

The Ohio Department of Natural Resources , Division of Geological Survey (ODGS) has an ongoing program for surficial mapping based upon creating a 1:00,000 scale USGS Quadrangle each year. The main component of these maps is creating a polygon which contains a three-dimensional “stack” which summarizes the gross lithologic material and thickness for the entire package of glacial/Holocene materials and finishes with the appropriate bedrock lithology at the base of the stack. Common lithologies include glacial till, ice-contact deposits, silty-clayey lacustrine deposits, sand and gravel deposits, etc. Thicknesses are reported in thicknesses of feet which are multiplied by a factor of 10. As an example, a polygon may contain a labeled stack such as T5/ SG3/ T2/ LS which would indicate this sequence contains 50 ft of till over 30 ft of sand and gravel over 20 feet of till over limestone bedrock. The maps are color-coded using the uppermost layer.

As of this date, the ODGS has mapped approximately 19 of the 34 complete or partial 1:100,000 quadrangles that cover Ohio. This progress includes a large portion of glaciated Ohio. The surficial maps contain information that is highly useful for water well drillers, construction activities, waste disposal and siting, and other planning activities.

The maps also have utility for the sand and gravel aggregate industry. To make a more useable product for this industry, the ODGS is creating a series of derivative maps based upon the 1:100,000 scale surficial geology “stack” maps. A series of queries were run for the GIS layers used to create the stacks to verify polygons with a thickness of sand and gravel units that exceed the thickness of overlying or interbedded finer-grained materials by at least a ratio of 4:1. The final resulting map is then color-coded based upon this ratio and also the total thickness of the sand and gravel units. A series of three smaller inset maps provide locations of sand and gravel mining operations, drift thickness, and the classic-geomorphic-based Quaternary Map of Ohio for the 1:100,000 scale quadrangle.