PALEONTOLOGICAL GEOLOGY 
69 
ocene” faunas, in the Cretacic where the former certainly belong 
and where the latter probably should be relegated. It assigns 
all the late Paleocene faunas to the Tertiary. 
The replacement of the Cretacic by the Tertiary vertebrate 
fauna would thus be a little later, and the substitution of the 
Late Cretacic by the Tertiary flora a little earlier, than the horizon 
agreed upon. Matthe:w. 
Physiographic Setting of Earliest Tertiary. The Rocky Moun¬ 
tain province is one which from earliest geological times has been 
one of the mobile tracts of earth. No similar belt on the face of 
the globe has so many diastrophic movements so plainly recorded. 
Abundant evidences of post-Paleozoic oscillations of the earth’s 
crust are still retained in the physiognomy of the Cordilleran 
uplift. 
Although in single rock sections it is rarely possible to evaluate 
in time units the magnitude or duration of erosion intervals as 
represented by unconformity lines there is no uncertainty on 
this score among the plantation levels of the southern Rockies as 
recently determined. There is no room for difference of opinion 
regarding whether a given orogenic movement belongs to a major 
or a minor category. The stratigraphic geologist is left in no 
confusion as to where to draw his taxonomic lines in the terranal 
column. 
Of the post-Paleozoic revolutions four are certainly in the 
major class for they are almost continental in extent. Coman- 
chan peneplanation reached from the Mexican tableland to the 
Canadian shield, and from the Pacific Ocean to the Mississippi 
River. The one distinguishing the Cretacic Period is hardly less 
extensive. It is known over the Cordilleran province as the Raton 
peneplain. Its erosional activities continued through Laramie 
times. In places the entire Cretacic section is removed. Its all 
but vanquished vestiges over the Rocky Mountain uplift of today 
are in the peak tops which rise above the summital plain. 
Along the Rocky Mountain front in the Mesa de Maya district 
especially, the Raton peneplain bisects horizontally a mile thick 
coal-bearing section that was long regarded as a Laramie succes¬ 
sion. But it itself really represents a Laramie hiatus. Above 
its level is a great thickness of epirotic deposits which are still 
