928 GEOLOGY OF OHIO. 
4. Roof coal or Rider seam.................068+ 24 to 4 ft. 
Third slate—Roof of entries, etc..........-....008 sere 4 to 4 inches. 
3. Upper bench of coal { ppacoal wasees 5) ito Gy it: 
Secondsslated).ccecwes othe atresia: eee ime Gee 2 to 4 inches. 
20 Middleibenchyolicoalemecccacsccsncccccc 5 to 5 in 
LO Wer SIALG 5. cti ee ieanes acess neues ve se ceamemes seme ceae ners x to # inches. 
I Bottomebenchioticoalleesccascciee cere 2 to 24 it 
Fire clay. 
A peculiarity of the structure is the reduction of the middle bench 
to such small proportions, smaller than is elsewhere found in this seam, 
but the bottom coal has full thickness and unusual excellence by way 
of compensation. | 
When the field was opened, it was popularly supposed that the 
entire 10 to 14 feet of the seam was available for the market, but those 
who understood the other districts of the ‘‘Great Vein” best, made 
but little account of the rider seam, and accordingly it was no great 
disappointment to such, to learn what the market soon taught, that the 
24 to 4 feet of this part of the seam must be left behind. The third 
slate in any case makes the safest roof under which to work, and the 
rider would not, therefore, ordinarily be taken until pillars were drawn. 
All of the coal below the third slate, aggregating 7 to 9 feet in thick- 
ness, was counted marketable, without a question, except that the upper 
portion was known to contain a layer of cannel or horn coal in places, 
and there was also known to be a suspicious band directly above the 
second slate. 
The cannel was found in quite large development in several of the 
Sunday Creek mines, lying two feet below the third slate, and being 
from 10 to 15 inches in thickness. This required the splitting of the 
top coal and effected a reduction of § of the thickness still counted 
available after the rejection of the roof coal. 
The remaining seven feet of the seam went forward to market, 
but serious complaints at once came back on the part of those using 
the coal. Wherever hot and constant fires were to be kept up, it was 
found that the Sunday Creek coal proved unsatisfactory, not from the 
character of the whole product, but on account of about $ of what was 
sent out. It did not take a long time to trace this inferior portion back 
to its location in the seam. It was found in a justly suspected locality, 
i, e., directly above the second slate, and, as finally worked out, was 
