CLASSIFICATION OF STRATIFIED ROCKS 677 
A second point is that, even in the definition of these systems, 
a degree of elasticity must be left for the geologists of different 
continents and countries. 
A third point is the adoption of a set of prefixes (Paleo, Meso 
and Veo) to be attached to the name of the system as a method 
of reaching comparative uniformity in the naming of divisions of 
the third order. 
The fourth point is the leaving to the local geologist, the 
task of selecting local geographic names for the divisions of the 
fourth order. 
Other points were discussed, but these are sufficient to show 
the trend of the discussions. 
When the report of the commission is published, a fuller 
presentation of the matter will naturally occur, but until then it 
seems to the writer that any attempt to make a more rigid classi- 
fication or nomenclature for general purposes is not to be 
desired. 
What we all are striving for is a scheme of nomenclature and 
classification by which we can clearly express and represent the 
grander conclusions of our science which are at present so much 
hidden by the multitude of details. But it is necessary to bear 
in mind, while seeking to attain this end, that refinement or 
uniformity in classification, or in methods of representing the 
facts, will not discover the principles coérdinating and determin- 
ing the relations of these facts to each other. The system of 
our classification must be based upon the knowledge already 
possessed, and so long as we have not discovered the clue to the 
great diversity presented by stratigraphic units, we must retain 
all the diversity they express in our detailed descriptions of 
them, and wait for uniformity in respect to the lesser matters 
until we discover the principles upon which the diverse phe- 
nomena are bound together into a systematic whole. 
It must be realized that many of these diversities, in name 
and relations to each other of the facts of geology, which con- 
fuse the student as his studies extend to details of the geology 
of other areas and other countries, are not due to different usage, 
