PALEONTOLOGICAL GEOLOGY 
73 
depositional equivalent of the Lance-Union conformity, obscure 
as that line now appears. The Union, Cannonball, and Lance 
formations manifestly represent provincial successions and there¬ 
fore each takes serial rank. Cannonball terrane is the attenuated 
margin of a greater rock-body the full development of which is 
to be looked for far to the north in Manitoba and Saskatchewan. 
K^yEs. 
Biotic Significance of Cannonball Fauna. Intercalation of an 
older sea fauna in the midst of a younger non-marine succession 
is not nearly so exciting a discovery as recent controversy would 
have us believe. There is merely again brought to sky’ the long 
known irreconcilable differences when objects are viewed in nar¬ 
row or diverse perspective. 
The recognition, in North Dakota, of the Cannonball terrane, 
with its characteristic thalassic fossils of Cretacic tenor, preceded 
and succeeded by thick deposits carrying distinctive non-marine 
forms and extensive land floras of admitted Tertiary affinities, 
strongly emphasizes the grave dangers of adhering too closely 
to a single fossil criterion in stratigraphic age determinations. 
The Cannonball incident is far from being an anomaly in geol¬ 
ogy. It is not even a strange or novel occurrence. There is repe¬ 
tition of it time and time again in the Coal Measures of Iowa, 
Missouri and Kansas. This very feature is one which Barrande 
so conspicuously paraded long ago in regard to the Cambric section 
of Bohemia. With this identical circumstance we are quite fa¬ 
miliar at the present day. In view of these facts the only question 
which really arises is: What criterion are we to follow ? 
It is not a question of which one we should give precedence to, 
our floral brethren, our invertebrate brethren, or our brethren 
attached to vertebrates, but whether we should consider the claims 
and conclusions of any of them. 
Careful analysis of the arguments advanced, pro and con, at 
once discloses the fact that in geological age determinations it is 
not really the rocks which are under consideration but the acci¬ 
dentally contained fossils, which of course is a very different thing. 
Just as in modern dredging operations in the Gulf of Mexico we 
find that the echinoderms, for instance, take on older and older 
aspect the deeper we go, until finally the deepest forms are strictly 
