GENETIC CLASSIFICATION OF PHENOMENA Sil 
the multitude of new conceptions and the maze of geographic 
forms that were presented, the analysis of the simple processes 
that were continually at work was largely overlooked. 
So far as I am able to see, Gilbert appears to be the only one 
who has yet struck the right chord in the attempt to classify, by the 
processes, geological phenomena. As long ago.as 1884 this writer 
proposed a “ Plan for a Subject Bibliography of North American 
Geology,” in which the geological agencies, instead of products 
are given primary consideration. How far the scheme would 
have been developed had it been allowed to go on cannot now 
be inferred. Since that time nothing further has been done in 
regard to this matter. The arrangement, presenting partly the 
common subdivisions of the subject of geology as given in our 
text-books, indicates that the author did not have in mind a 
classification that can be regarded as strictly genetic. 
A few years later McGee suggested ‘‘a purely genetic tax- 
onomy of geology, designed to include geography.” This plan 
is particularly instructive as illustrating another phase of the 
subject. A critical examination of the scheme clearly shows that 
it is not really genetic except in name. Each product is made 
to have a constructive and a destructive phase. This plan has 
been, it may be here mentioned, seized with avidity by the more 
progresssive geographers. Its method is particularly attractive 
when applied to topographic forms, especially since it has been 
fully recognized that they all have “‘life histories.” It is mani- 
fest, however, from the whole treatment of the theme that this 
plan has for its actual foundation the product and not the pro- 
cess. Stages of construction and of destruction must necessarily 
center around the feature and not theagency producing it. The 
essential characteristic of this scheme is the twofold nature of 
the production of every geographic form. When it is remem- 
bered that in the old geology the product is the all important 
factor, and in the new the process, it is at once seen that the 
dual plan is based entirely upon the old conception, and that 
the truly genetic principle is lost. 
The plans of classification by genesis that have been formu- 
