Coal Mine Source Maps
Mine outlines depicted on the
map are, whenever possible, based on maps made from original mine surveys.
The process of compiling and digitizing the quadrangle map may produce small
errors of less than 200 feet in the location of mine boundaries. Larger error
of 500 feet or more are possible for mines that have incomplete or inaccurate
Because of the extreme complexity of some mine maps, detailed features of
mined areas have been omitted. The digitized mine boundary includes the exterior
boundary of all rooms or entries that were at least 80 feet wide or protruded
500 feet from the main mining area. Unmined areas between mines are shown if
they are at least 80 feet wide; unmined blocks of coal within mines are shown
if they are at least 400 feet on each side. Original source maps should be consulted
when precise information on mine boundaries or interior features is needed.
The mine summary sheet lists the source maps used
to determine each mine outline. The completeness of map sources is indicated
on the map by a line symbol at the mine boundary. Source maps are organized
in five categories.
- Final Mine Map: The mine outline was digitized from an original map
made from mine surveys conducted with a few months after production ceased.
The date of the map and the last reported production are listed on the summary
- Not a Final Map: The mine is currently active or the mine outline
was made from a map based on mine surveys conducted more than few months before
production ceased. This implies the actual mined-out area is probably larger
than the outline on the map. The mine summary sheet indicated the dates of
source maps and the last reported production, as well as the approximate tonnage
mined between these two dates (if the mine is abandoned). The summary sheet
also lists the approximate acreage mined since the date of the map and, in
some cases, indicated the area where additional mining may have taken place.
This latter information is determined by locating on the map the active faces
relative to probable boundariesof the mine property.
- Undated Map: The source map was undated, so it may or may not be
based on a final mine survey. When sufficient data are available, the probable
acreage of the mined area is estimated from reported production, average seam
thickness and a recovery rate comparable to other mines in the area. This
information is listed in the summary sheet for the mine.
- Incomplete Map: The source map did not show the entire mine. The
summary sheet indicates the missing part of the mine map and the acreage of
the unmapped area, which is estimated from the amount of coal known to have
been produced from the mine.
- Secondary Source Map: The original mine map was not found so the
outline shown was determined from secondary sources (e.g., outlines from small-scale
regional maps published in other reports). The summary sheet describes the
Land Reclamation Division