Description: World Latitude and Longitude Grids represents a 1- by 1-degree latitude-longitude grid covering the world with attributes that allow it to display grids at intervals of 1, 5, 10, 15, 20, and 30 degrees. To display a grid with a 1-degree interval, simply display all of the lines. To display a coarser grid (e.g., a 15-degree interval), in the Layer Properties dialog box, add the DEGREE15 attribute value equal to Y.
Name: Map 5: Structure Contours of the Top of the Pennsylvanian Springfield Coal and Bevier Coal (Missouri)
Display Field:
Type: Group Layer
Geometry Type: null
Description: This map, the first structure-contour map, shows the variation in elevation of the top of the Springfield Coal, a Pennsylvanian stratigraphic marker horizon in the Illinois Basin.
Name: Map 7: Structure Contours of the Top of the Ordovician Trenton Limestone (or Equivalent)
Display Field:
Type: Group Layer
Geometry Type: null
Description: This map shows the variation in elevation of the top of the Trenton Limestone, a unit deposited near the end of the Ordovician. The Trenton is the deepest sedimentary unit contoured. Its elevation clearly shows the shape of the Illinois Basin, the Rough Creek Graben, and the Cincinnati Arch. The color of this map coincides with the color of the Ordovician Stage rocks depicted on the Bedrock Geology with Bedrock Topography map (Map 4).
Name: Map 8: Structure Contours of the Top of the Precambrian
Display Field:
Type: Group Layer
Geometry Type: null
Description: This map shows the elevation of the top of the basement (i.e., the unconformity at the base of the Cambrian and the top of the Precambrian; Figure 9). It has been shaded and colored to emphasize the shape of regional-scale epeirogenic structures. The most striking feature of the map is the 25,000 ft (7,600 m) of structural relief between the Precambrian outcrops of the Ozark Plateau and the Illinois Basin. East of the Illinois Basin in central Kentucky, a narrow “bridge” of basement upland connects the Rough Creek Graben and the southern end of the Rome Trough.
Description: This map provides a subset of data made available by the U.S. Geological Survey (USGS) that displays the gravity anomaly data for the OIINK study area.