72 
PALEONTOLOGICAL GEOLOGY 
which such a schematic arrangement of terranes may have 
over any other lies in the circumstance that it is genetic in its 
nature, and that it has as its foundation the very same agencies 
which make the recognizable changes in sedimentation possible. 
Diastrophism finds best expression in mountain uplift. The 
preservation of its record finds best expression in peneplanation 
and in the more ancient erosional unconformity plane. From 
these unconformity planes new sedimentive records arise. With 
extensive geological mapping accomplished a continental network 
of uncomformities is produced for the whole geologic column. 
The taxonomic value of each unconformity is then directly 
proportional to its lateral extension. 
Terranal classification becomes feasible without dependence upon 
faunal or floral content. Such a classificatory scheme is as much 
superior to the biotic one as was the latter over the lithologic one 
a hundred years ago. 
Analyzing the relations of the Lance formation according to its 
diastrophic affinities, recognizing the unconformity at its base as 
one of major rather than minor order, and taking cognizance of 
the fact that no other majpr planation occurs in the continental 
interior until Miocene time the Lance formation falls easily and 
naturally into the Tertiary section of the regional geological 
column. 
This may not agree very closely with the course of vertebrate 
evolution, or invertebrate development in the region, but rock 
classification based upon either of them is not terranal classifica¬ 
tion at all, but merely a faunal one. There can be no genetic 
connection between diastrophism and biotic expansion. At best 
the latter may only be slightly modified by the former. So, with 
irreconcilable differences between the several biotic lines of evi¬ 
dence in the Lance-Union controversy, as well as many other 
similar ones, the time and opportunity seem propitious for the 
geologist in all taxonomic problems to put chief stress on the 
diastrophic movements, and break away from the antiquated and 
unrelated biotic criteria in terranal classification. 
From the viewpoint of the diastrophist the inclusion of the 
Cannonball formation with the Lance succession is clearly a 
mistake of observation. It is hardly the marine equivalent of the 
Lance section, but altogether younger. It seems to be rather the 
