STRATIGRAPHIC TERMINOLOGY 1107 



instead of stage. The terminations of the names of the systems 

 are not altered to correspond to that adopted by the Congress. 



Unification of Terminology. 



In the development of the classification of the geologic forma- 

 tions, the systems were gradually introduced either by intercalation 

 of a previously unknown system between two well-established ones, 

 as the Devonian between the Silurian and Carboniferous ; or by 

 the separation of the new system from an older one with which it 

 was formerly included, as Ordovician from Silurian. No uniform 

 method of derivation of these names was followed, though the 

 majority of names had a geographic origin. Neither was uni- 

 formity of termination considered, though among the later-formed 

 names ian was generally selected. This heterogeneous terminology 

 has become so firmly embodied in the framework of stratigraphic 

 classification that it probably will be a long time before we can 

 hope to replace it by a more homogeneous one. Such terms as 

 Carboniferous are wholly out of harmony with the majority of 

 other terms and ought to be discarded. But the adoption of a 

 uniform termination of these names, as suggested by the Congress, 

 and as is widely practiced, particularly in Europe, will do away 

 with the most objectionable part of this terminology and bring it 

 into harmony with the remaining portion of the scheme. In the 

 table on p. 1108 the systems used in this work are given with the 

 termination used by the International Congress, and with it the 

 old heterogeneous termination. The author and derivation of each 

 term is given. (See also table on page 22.) 



A tendency toward splitting up some of the larger systems and 

 uniting others has been shown by many stratigraphers. The 

 Palseocenic has been introduced in the Cenozoic and united with the 

 Eocenic and Oligocenic as Palseogenic ; Miocenic and Pliocenic have 

 been united as Neogenic ; and Pleistocenic and Holocenic as Ceno- 

 genic. The Liassic has also been separated as a distinct system by 

 some European stratigraphers. Recently this method of subdi- 

 vision has been carried to great extremes in the works of Schuchert 

 and Ulrich, to which the student is referred (14; 17). The sub- 

 divisons advocated by Ulrich are more extreme than the facts seem 

 to warrant, and they have not generally been adopted. 



Local Stages and Suhstages. Generally, detailed study of a 

 Hven region will show the occurrence of numerous local forma- 



