4 Geological Survey of Alabama. 



illustrating both his own and Dr. Meyer's articles. The only cost to the 

 State is for the printing of a few pages of ordinary letter-press. 



In answer to the possible question as to what practical or economical 

 value such work may have, it may be stated that there are at intervals 

 through the Tertiary deposits of Alabama, ten or fifteen horizons at 

 which occur beds of marine shells. In many cases these are closely asso- 

 ciated with green-sands and other materials of economic value, the recog- 

 nition of which becomes thus often a matter of importance. 



The association of the shells in these marine deposits is always such 

 that the different beds may in general be very easily identified and dis- 

 tinguished from each other by any one even moderately well acquainted 

 with their fossil contents. 



These shells thus become most valuable guides by which the geologist 

 is enabled to recognize the identity of strata widely separated geograph- 

 ically, and differing widely in the character of the materials of which 

 they are composed. 



With the small appropriation available for the purpose of the survey, 

 I should have hesitated to expend any of it upon a subject like this, 

 which, while it has, as above shown, very important practical and eco- 

 nomical bearings, might yet be looked upon as of comparatively little 

 utility to the majority of the people of the State ; therefore, our thanks 

 are due to Mr. Aldrich for coming to our aid, both as a writer and 

 financially. 



EUGENE A. SMITH. 



UNIVERSITY OF ALABAMA, July 1, 1886. 



