This is a shapefile of the Oak Openings sand ridge in northwest Ohio. 
The general outline is taken from the Ohio Department of Natural Resources 
Unconsolidated Aquifers of Ohio map. Area outlined is known as the 
"Oak Openings Ridge". Shapefile stops at the Michigan border but ridge 
actually continues to around Pontiac, MI.  This shapefile only includes
the main ridge of the Glacial Lake Warren and Wayne stages.