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

14 ILLINOiS BASIN COAL RESOURCES
In the accompanying analyses (table 1 ) ,
moisture values are not representative because
the samples were subjected to high
gravity separation liquids to remove rock
impurities and to several stages of washing
and drying to remove traces of the drilling
mud. In general these coals display a relatively
high fixed carbon content which is
associated with a fairly high unit coal heat
value. These are characteristics that might
indicate coal of relatively high rank, particularly
when unit coal B.t.u. values exceed
14,700 which is generally higher than the
B.t.u. value of the coal mined anywhere in
the State except in Saline and Gallatin
counties.
Because of the very small amount of information
available in regard to the coal
beds penetrated in the Illinois basin, the
Survey would be glad, so far as our facilities
allow, to analyze samples of coal cuttings
representing beds of workable thickness,
irrespective of depth, penetrated in cabletool
or rotary-drill holes in the Illinois basin
or in Edgar, Crawford, Clark, or Lawrence
counties. The sample should weigh not less
than about one-half pound, consisting of
coal that will float on liquid having a
specific gravity of 1.5.
Use of electric logs in determining coalbed
thick7zess.-After much study of the
electric logs of rotary-drill holes of the
standard form, including normal and third
resistivity curves and potential curves, and
of the records of the cores of diamond-drill
holes and electric logs of the same holes, it
is apparent that the electric logs do not
generally provide a satisfactory record of
coal-bed thickness or of the thickness of
accompanying thin beds of black shale,
limestone, and underclay. In the present
series of reports, therefore, estimates of coalbed
thickness are based solely upon information
obtained at the drill holes logged by the
Survey field parties. Detailed mapping of
variations in thickness of No. 6 and/or No.
5 bed, as was done for Wayne County,14 is
not attempted.
*ZRept. Inv. 93, pp. 30, 31, 1941.
The task of logging the 66 drill holes
located in Clay, Edwards, Gallatin, Hamilton,
and Richland counties, since the start
of this project early in 1942, has been shared
by 24 individuals, all but one of whom were
members of the Coal Division of the Survey
staff. The field parties consisted of from
two to four men, and different observers
have assisted in the logging of from one to
30 drill holes. Of the group, only R4.
William Pullen has been in continuous
employment with the Survey during the
period. The following persons have assisted
in logging the drill holes in these
counties, the number of holes observed being
indicated in parenthesis (see also table 2) :
A. F. Agnew (12) ; A. L. Brokaw (11);
M. G. Caplan (1); E. P. DuRois (1) ; A.
L. Eddings ( 11 ) ; R. W. Ellingwood (5) ;
K. Gutschick ( 1 ) ; T. V. N. Karlstrom
('7) ; D. F. Kent (8) ; R. M. Kosanke (3);
H. A. Eowenstam (9); J. N. Payne (5);
&/d. W. Pullen (30) ; K. R. Reynolds (8);
J. M. Schopf (2); R. Siever (8) ; J. A.
Simon (1) ; P. K. Sims (15) ; H. L. Smith
(22); R. F. Smith (5); R. F. Strete (4);
and G. M. Wilson (7). Their assistance
in this important part of the project is
gratefully acknowledged.
The study of the drill cuttings was carried
on to a large extent by one or more of the
persons who logged the drill holes, but
numerous sets of cuttings were examined
and logs compiled by Margaret A. Parker
and Mary Barnes Molley. One set was
studied by R. C. Honea, Jr.
In the preparation of base maps of the
various counties and in the drafting of maps
and charts the authors were assisted by
Arnold Eddings, Elizabeth P. Lohmann,
Flo Nel Ozelsel, Robert W. Ellingwood,
and George E. Ekblaw. Topographic
maps were used so far as available in the
preparation of base maps, and beyond this,
much help was obtained by using aerial
photographs made by the Agricultural Adjustment
Administration loaned by the
Library of the University of Illinois.