350 A SYMPOSIUM 



meanings somewhat, rather than discard them altogether. 

 Besides they have entirely lost their local original significance. 

 They are now abstract terms. In this country the data will 

 soon be at hand for the construction of an entirely new chrono- 

 logical plan, having a purely physical basis, the biological 

 criteria being ignored altogether. 



In the third order there is an overlapping of general and 

 local criteria. To express the time factor the words Early, Mid- 

 or Middle, and Late appear appropriate ; as Early Cretaceous. 

 The simple Anglo-Saxon names are much more preferable than 

 the long barbarisms, produced by the Greek prefixes Eo, Meso 

 and Neo. Simplicity of terminology should be a cardinal prin- 

 ciple if geological science is ever to receive the popular atten- 

 tion it deserves. For the rock scale, Lower, Median or Middle, 

 and Upper are useful terms to indicate in a general way the cor- 

 responding subdivisions ; as Lower Cambrian, Lower Carbonifer- 

 ous. Or, the latter titles may be used in a somewhat indefinite 

 way, when the exact stratigraphic limits are yet unknown. 



Here the local succession begins to assume importance and 

 the general time factor to lose it. Each geological province 

 has its own sequence of strata. A provincial geographic name 

 is desirable, if possible with an adjective ending. Thus, we have 

 for the Lower Carboniferous in the Mississippi province, the 

 Mississippian series ; in the Appalachian province the Poconon 

 series, possibly ; in the Great Basin province the Aubreyan 

 series, perhaps. The number of series is thus not fixed for any 

 system, as locally represented, nor for different localities. Yet 

 the epoch of all is definite. The time may come when it is 

 desirable to have some special name to coverall the provincial 

 series of approximately the same age, but the condition of our 

 knowledge does not yet warrant it. It is doubtful whether it 

 would be any improvement on the simple Lower, Middle and 

 Upper. 



An ideal feature of geological nomenclature is uniformity 

 of endings for all terms of equal taxonomic rank. With those 

 of the first order this method already prevails. In the case of 



