WESTERN COAL MEASURES AND INDIANA COAL. 549 
alike favorable for the formation of coal, and that, while the ocean 
was excluded from the Appalachian sea, where the material for 
coal beds was forming. The sea on the Western side was still 
filled with salt water, where the sediment was accumulating which 
was subsequently changed to rock, and the conditions favorable to 
the production of coal had not yet been reached. Such a state of 
things will serve to account for the great discrepancy in the aggre- 
gate thickness of the strata in‘the two coal fields. The Appala- 
chian, being estimated at twenty-five hundred or three thousand 
feet, whereas, in the Western coal field, the greatest depth will 
hardly exceed one thousand feet; and in Indiana, not more than 
seven hundred feet, if so much; though we include, in the latter 
estimate, every stratum from the Archimedes limestone upward. 
From observations made in the Western coal field, during the 
past three years, extending over portions of southern Illinois, 
western Kentucky, and Indiana, so many errors have been found 
in the sections of the coal strata given in the third Kentucky Re- 
port, and which were pretty generally copied by other geologists 
in more recent reports, that I have found it necessary to make an 
entirely new classification of the coals in the west. 
In the connected section of the Western coal beds, given at pages 
18-24, 3d vol. Ky. Report, the measures are divided into upper 
and lower coal measures, and this arrangement, with some local 
modifications, has, until recently, been generally adopted by geol- 
ogists. Now, so far as my observations go, either in Kentuc 
Illinois or Indiana, I can find neither lithological nor palzeontolog- 
ical evidence which can be relied upon for cutting up the Western 
coal measures into separate epochs. The Anvil Rock sandstone, 
which was brought into requisition for this purpose, can hardly be 
depended upon as a horizon, beyond the small district in which it 
was first discovered, and the equivalency of the Mahoning sand- 
stone of the Pennsylvania geologists, as designated by Owen and 
Lesquereux, has also proved totally unreliable as a basis for divi- 
sion, even though it should be found necessary to establish one. 
In the 3d vol. Ky. Report, and in the Report of a Geologi 
Reconnoisance of Indiana, 1859, the latter stone is at one place 
referred to the horizon of the Anvil Rock sandstone, and at 
another locality to that of the Millstone grit. 
Indeed, so unfortunate has been the effort to transplant the Ma- 
honing sandstone of Pennsylvania into our western coal measures, 
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