514 THE JOURNAL OF GEOLOGY. 



been added to the volume. A small edition of the first part of 

 this volume (economic) was issued separately in December, 

 1893, but it is also included in the volume that is now in the 

 binder's hands. 



Among the principal results thus far obtained in the investi- 

 gation of the geology of the State at the public expense the 

 following may be named : 



1. The order, mineral composition and thickness of the 

 leading elements of our scale have been determined, and their 

 outcrops have been mapped with all needful accuracy. 



2. The salient features of the geological structure of the 

 State have been brought clearly to light. 



3. The paleontology of the State, while it has not been 

 treated systematically or symmetrically, has still received a con- 

 siderable measure of attention and expenditure. Hall, Meek, 

 Whitfield, Newberry, and Cope have made contributions of great 

 value to our knowledge of the fossils of our series. 



4. A great deal has been done in the interests of our eco- 

 nomic geology. Chemical analysis has been applied to our lime- 

 stones, cement rocks, clays and building stones, by no means 

 exhaustively, but still fully enough to furnish safe, practical 

 guidance to our people in every section of the State. But it is 

 to the coal fields of Ohio that the largest measure of service has 

 been rendered. The several seams have been carefully mapped 

 so that the areas of each above drainage are known (Vol. VII.), 

 the order of the seams has been definitely settled with a few 

 unimportant exceptions, and correlations have been established 

 with the Coal Measures of Pennsylvania, Kentucky, and West 

 Virginia. The analyses of our coals have been made on a system 

 that renders the figures fairly representative, and they accord- 

 ingly command universal confidence in the markets of the coun- 

 try. The mode of occurrence of oil, gas, and salt water in the 

 State has been carefully studied, and the search for these ele- 

 ments of mineral wealth has been aided and rationalized thereby, 

 to some extent. 



As to what remains to be done, it is not necessary to speak. 



