PALEONTOLOGICAL GEOLOGY 
63 
and insects. Both these groups have practices whereby the 
animals can go for long times in a dormant condition, the snails 
withdrawn in their shells, the insects in a pupa condition or even 
in hibernation. These conditions make it fairly easy for the 
animals to be transported long distances. Considering the direc¬ 
tions of the oceanic currents and the distribution of these groups 
in South America, it appears patent that this was the manner in 
which they were distributed. The evidence from the Glossopteris 
flora needs very careful scrutiny before being used. It is not 
known yet whether the peculiarities of this flora are due to clima¬ 
tic adaption or not, and until more than the shape of leaves is 
used for comparison it is not a safe line of argument for postulat¬ 
ing connections from one continent to another. 
Loomis 
Stratigraphy of Black Hills Tertiaries. The recent discovery 
of a distinctive Cretacic marine fauna in the midst of a thick rock- 
section northeast of the Black Hills that was long regarded as a 
freshwater deposit. Tertiary in age, renews that long standing con¬ 
troversy over the proper stratigraphic horizon on which to separate 
Cenozoic from Mesozoic sedimentation. 
In North Dakota a formation called the Lance in Montana, is 
divisible into three members. The lower terranes have close bio¬ 
tic affinities with the overlying Tertiary Union beds, but the upper 
member carries the typical Fox fauna which normally occurs far 
beneath. The section is: 
White River sandstones.Feet 140 
Unconformity 
Union shales.10<K> 
Cannonball (Marine) shales. 300 
lyudlow lignites. 350 
Bllackhorse shales*.v. SCO 
Unconformity 
Fox sandstones. 400 
Pierre shales (exposed). 500 
The diastrophic setting is that of marked crustal uprising 
followed by notable down-sinking, expressed by a retreating sea 
succeeded by a moderate advance over slightly tilted shore deposits. 
It is probable that when more careful inspection is made than has 
* Blackhorse Butte is a conspicuous landmark in Schanasse County, South Dakota, 
and overlooks the Grand River Valley, and the basal shales of the Dance. 
