PREFACE. xi 



20,000,000,000 tons by the first computation and 12,000,000,000 tons by the second. 

 Even when thus reduced, the figures pass far beyond all intelligible conception. 



For how long a time would such amounts of coal last? That, of course, de- 

 pends upon the rate of annual consumption. In 1892, the output of Ohio mines 

 was 13,500,000 tons. Since mining has been going on in the large way in the State 

 the production has been doubled in periods of about ten years. At this rate the 

 annual production will reach 25,000,000 tons a year, early in the twentieth century. 

 Supposing it to run steadily at this point, Ohio coal would last about eight hundred 

 years on the basis of the first measurement and less than five hundred years by the 

 second. But, if the rate should continue to advance as it has done heretofore until 

 an annual output of a hundred million tons is reached, the duration of the supply 

 would be correspondingly diminished, viz., to two hundred and one hundred years, 

 respectively. 



I look to see our mining engineers avail themselves of the above named 

 boundaries, now for the first time provided for them, and proceed along 1 different 

 lines of theory and investigation to determine the coal resources of particular fields 

 or definite areas. 



In conclusion, a few words will be devoted to a review of what has been already 

 accomplished by the several geological surveys of this State, and to a brief consid- 

 eration of what remains to be done. 



1. The general stratigraphical order of our several formations is now fairly 

 well determined; so far, at least, as their occurrence within our State boundaries is 

 concerned. Their correlation with the series of neighboring states leaves some- 

 thing to be desired. This is especially true of the northeastern corner of Ohio. 



2. The leading features of our economic geology have been set before the peo- 

 ple of the State so that land owners of ordinary intelligence can acquaint themselves 

 with the probable value of their mineral resources. They are no longer at the 

 mercy of men who are able to take advantage of their ignorance. 



3. The salient features of our paleontology have been made intelligible to all 

 of our people who take an interest therein. 



As to what remains to be done in Ohio geology, it is difficult to speak. The 

 science of geology is constantly lengthening its cords and strengthening its stakes. 

 Every line of investigation opens up larger questions than those which it directly 

 undertakes to settle. New methods of research are coming into use, and old prob- 

 lems must be reconsidered by their aid. It is only the generalities of our geology 

 that have been thus far attacked. Deeper and more thorough work will be de- 

 manded in every subdivision of every field. It remains to be seen, how much of 

 this more refined study will be carried on at the public expense under State direc- 

 tion. Speculation upon this point is unnecessary. 



There are, however, several subjects that could well bear more investigation of 

 the type that r as been thus far maintained than they have received. The I,ower 

 Helderberg limestone and the Ohio Shale, in particular, furnish excellent subjects 

 for more careful stratigraphical and paleontological determination. 



The drift formations, glacial and post-glacial, of the State, have thus far been 

 studied in a very superficial way. It is but recently that methods have been devised 

 for taking better account of their complex history. Closely connected with these 

 deposits, is the consideration of the pre-glacial drainage systems of the State. The 

 little study that has already been given to these subjects reveals their highly inter- 

 esting character. Further investigation in these lines is sure to bring ample reward. 



It cannot be denied that during the progress of the survey, the great interest 

 of Agriculture has received less direct attention than, in the beginning of our work, 

 it was led to expect and much less than its intrinsic importance would warrant it in 

 demanding. There are two principal reasons for this neglect, first, that the geolog- 



