subsurface geology and coal resources of the pennsylvanian system ...

68 ILLINOIS BASIlV COAL RESOURCES
the heavier portions of the coal are likely
to concentrate in the samples and thus may
have a higher sulfur content than the coal
as a whole. The fairly high sulfur content
of these samples probably indicates a relatively
high sulfur content in the bed.
OIL AND GAS RESOURCES
Although the structure maps accompanying
this report provide a general picture of
the "lay" of the coal-bearing strata in Edwards
County, they are not designed to delineate
oil and gas structures. In the first
place, not all available data were used, and
in the second place, the structure has been
delineated according to engineering methods,
without the liberties in interpretation that
usually characterize oil and gas structure
mapi. Consequently the structural irregularities
shown, although they may correspond
in some places with the position of
oil and gas pools, can scarcely be expected
to do so consistently, and the maps are not
regarded as particularly suitable for forecasting
the position of undiscovered oil and
gas accumulations.
CONCLUSION
In this study of the Pennsylvanian beds
of Edwards County emphasis has been
placed upon the coal beds and limestones
in the McLeansboro and Carbondale groups.
The stratigraphic logs compiled from cuttings
carefully collected from control wells
at close intervals and drilling time records
of the same drill holes have been the principal
source of information. They have provided
a means of interpreting electric logs
of adjacent drill holes. Study has been
made of about 330 such electric logs and of
the logs and cuttings from two cable-tool
holes. Much more detailed information in
regard to the stratigraphic succession in the
McLeansboro and Carbondale groups is
available in the cuttings that have been collected
from the control wells than was
possible or necessary to assemble for the
purposes of the present report. This is
particularly true of the beds above the West
Franklin limestone and those below the
Palzo sandstone.