154 Prof. Rogers's Address before the 



We are therefore constrained to view the whole as constituting a single 

 system, the entire record of one immense continuous period, the col- 

 lected gatherings of one prodigious sea. To deduce from a study of 

 the organic remains of the different portions of this mass, aided by con- 

 siderations of mineral type, a classification which shall be in harmony 

 tvith the natural relationships of the different members throughout the 

 entire basin, as to time and circumstances of origin, one which, in other 

 words shall express the various epochs and changes in their relative 

 importance ; and to clothe this classification in language which shall be 

 at once suggestive of their relationships and generally applicable, fur- 

 nishes a complex problem of much difficulty, but one perhaps which 

 at the present time has strong claims to the attention of American 

 geologists. 



As the necessity for a general nomenclature for these rocks, founded 

 on a wide survey of their fossils, is getting to be recognized, as many 

 and grave objections exist to the adoption of all local and partial classi-. 

 fications, and as it is believed that through the diligence of our geolo- 

 gists, we are already prepared with a sufficiently ample body of data 

 for the construction of a system which shall unite the chief requisites 

 here mentioned, I venture, craving the indulgence of the Association, to 

 present the outlines of a scheme of grouping and naming our Palseo- 

 zoic strata, which my brother Prof. W. B. Rogers and myself, have 

 been carefully maturing during the last three years. 



We propose to distribute the whole great body of strata from the base 

 already designated to the top of the coal measures in nine distinct series^ 

 the products of as many great successive periods, and resorting to the 

 analogy between these periods and the nine natui'al intervals into which 

 the day is conveniently divided, we have named them in ascending or- 

 der, the primal, maiinal, levant, premedidial, medidial, post.medidial, 

 ponent, vespertine and serai series, the deposits of the dawn, morning, 

 sunrise, forenoon, afternoon, sunset, evening and twilight periods of the 

 great Appalachian Palfeozoic day. Subdividing each series in obedi- 

 ence to natural and obvious relations of the organic remains and miner- 

 al boundaries, we have named each ultimate subdivision or formation^ 

 calling the time during which each formation was produced an epoch, 

 and between the series and formations, we have constructed groups m 

 all cases where the natural affinities of the formations require that two 

 or more of these latter shall be united into associations subordinate to 

 the series. 



