Explanation of Coal Bed Mapping Project GIS Coverages

• Structural contours*: The vector (line) structural contours coverage documents the change in elevation above sea level of the base of the coal bed. The labels are scale-dependent, and will become visible as you zoom in past a scale of 1:200,000.

• Elevation control points: The elevation control points are the locations where the elevation of the coal bed has been recorded. These data were used to create the structural contours coverage.

• Coal map boundaries: This vector coverage outlines the area of the coal bed as mapped to date. Boundary types include the outcrop line, or surface trace, representing the intersection between the coal bed and the land surface; the stratigraphic edge of the bed, where the bed becomes absent in the rock column (for example, coal thins out, or a channel feature); the temporary extent of mapping to date; the final extent of mapping, (for example, near a state line); and the adequate data control boundary, beyond which data is insufficient to map the bed.

• Coal Bed Split/Merge*:This vector (line) coverage outlines an area where two (or more) coal seams have merged together into one coal bed. In such areas, peat accumulation was less frequently interrupted by sedimentation, resulting in more net coal and fewer, thinner rock partings. In areas closer to fluvial (river) channels, more frequent and higher volume sedimentation events resulted in temporary cessation of peat deposition and the creation of two or more coal “splits” separated by thick rock units. The Split/Merge line approximates the boundary between where the “splits” are merged into a logical mining unit and those areas where each “split” has been mapped as a separate mining unit. Customarily the merged coals take the name of the "major" bed, which is usually the more regionally extensive and persistent coal seam. The "minor" bed is usually the less significant or less extensive coal bed, but not necessarily the thinner seam. The merged area of the coal seam is included in the map of the major coal bed, and is shown as a blank, cut-out area of the minor coal bed map, bounded by the Split/Merge line.

• Mined and remaining coal areas*: This polygon coverage divides the mapped area of each coal bed into polygons of mined areas, and unmined (remaining resource) areas. The mined areas are further differentiated by method of mining, including underground, surface, or auger methods. Information on underground mines such as the mine name, company name, and permit number, is available by using the identify tool on the mine polygon. The outer boundaries of this coverage are identified in the coal map boundaries coverage.

• Aperture card labels*: The underground mine polygons are constructed from detailed maps of underground mine workings. WVGES has a collection of aperture cards, each containing an image of a mine map or part of a mine map on a 35mm film frame. These aperture cards are obtained from the US Department of Interior, Office of Surface Mining, Mine Map Repository. Some underground mine polygons in the mined and remaining coal area coverage are compiled from more than one aperture card. The polygon is attributed with the number of the principal card, and the remaining aperture cards used are indicated by the aperture card labels that fall within the polygon.

• Mining extent unknown: This vector coverage indicates where the boundary of an underground mine is unknown. Some maps of underground mines are "cut off" or are incomplete and no document (to date) is available of the entire mine.

• Geological discontinuities*: These are features encountered in underground mining that disrupt mining, such as stream channeling (washouts) contemporaneous or penecontemporaneous with peat deposition, geologic faults, areas of uncontrollable roof or floor, excessive parting, or other local features.

• Total bed thickness*: This polygon coverage documents the variation, in 12-inch increments, of the total thickness (or height) of the bed including coal and non-coal partings. Similar color schemes are used for all colored polygon maps: red, yellow, and orange colors indicate less desirable areas from a resource utilization point of view, while increasingly darker greens indicate more desirable areas.

• Net-coal thickness*: This polygon coverage documents the variation, in 12-inch increments, of the thickness of coal only, excluding non-coal partings in a bed. Similar color schemes are used for all colored polygon maps: red, yellow, and orange colors indicate less desirable areas from a resource utilization point of view, while increasingly darker greens indicate more desirable areas.

• Percent parting*: This polygon coverage documents the variation of the amount of non-coal material, or partings, in the bed expressed as a percentage of the total bed thickness in 5 % increments. Similar color schemes are used for all colored polygon maps: red, yellow, and orange colors indicate less desirable areas from a resource utilization point of view, while increasingly darker greens indicate more desirable areas.

• Thickness control points: These are the locations where the thickness of coal and partings within a coal bed have been recorded. These data were used to construct the total bed thickness, net-coal thickness, and percent parting coverages.

• Variation in coal quality parameters such as sulfur and ash content. (Under construction.)

Other coverages available to the user in the interactive maps include:

• WV County outlines* This layer is scale-dependent, and will disappear once you zoom in, or zoom out, past a certain scale. County name labels are also scale-dependent, and will appear once you zoom in past a certain scale.
• WV 7.5-minute quadrangle outlines* This layer is scale-dependent, and will disappear once you zoom in, or zoom out, past a certain scale. Quad name labels are also scale-dependent, and will appear once you zoom in past a certain scale.
• Georeferenced image mosaics of the USGS 7.5-minute topographic maps: These are tiled scanned images of the most recent topographic quadrangles published by the US Geological Survey. Generally, most recent updates shown on these maps are from the 1970's, although revision dates vary. Therefore, some houses, roads and buildings may not be shown exactly as they are today. A quadrangle mosaic (in MrSID format) is available for each completed study area: The Northern Panhandle study area, the Monongalia, Marion, and Harrison counties study area, and the Fayette-Raleigh County study area.