The computer-derived contours and color ramp on this map show the net thickness of the Devonian-Silurian carbonate rock resource in Bartholomew County. The shaded relief on the map shows the modern topography. The Devonian and Silurian carbonate rock resource consists of the rocks from the top of the North Vernon Limestone to the unconformity at the base of the Silurian. It includes the following map units shown on the Bedrock Geologic Map of Bartholomew County, Indiana (Hasenmueller and Rupp, 2017a): North Vernon Limestone (Devonian); Jeffersonville Limestone, upper unit (Devonian); Jeffersonville Limestone, Geneva Dolomite Member (Devonian); Wabash Formation, Mississinewa Shale Member (Silurian); Louisville Limestone and Waldron Shale undifferentiated (Silurian); Salamonie Dolomite (Silurian); and Brassfield Limestone and Sexton Creek Limestone undifferentiated (Silurian). These rocks are an economically important resource for two reasons (Table 1): first, they are a major source of crushed-stone products (Carr and others, 1971), and second, they compose a major bedrock aquifer unit (Lloyd and Lyke, 1995; Maier, 2004).