PROCEEDINGS. 
501 
graphically or in a model, to their intersections; care is, however, neces¬ 
sary not to be misled by the development of theoretical planes beyond 
reasonable limits. 
As a result of many determinations of hade, it is found that faults in 
southwestern Virginia and northeastern Tennessee hade to the upthrow 
at angles ranging from forty-five to seventy degrees from the vertical. 
The Neozoic Formations in Arkansas, by Mr. R. T. Hill. 
[Abstract.] 
The Neozoic formations of the Southern Gulf States have been studied 
mostly from long range, from which only the hand rock material and 
conspicuous fossils, both exceptional features, were visible and from which 
no ideas whatever of their relation, differentiation, and stratigraphic 
paleontology are conceivable. Southwest Arkansas, notwithstanding the 
obscurement of the stratigraphy by the dense forest growth and debris, 
afforded a fair-cross-section of the Neozoic formations and the method in 
which they were deposited one upon the other and upon the older Paleo¬ 
zoic continental area. 
During the past year, under the direction of Dr. John C. Branner, State 
geologist of Arkansas, Dr. Hill commenced a systematic investigation of 
the economic questions of the region, to facilitate which he was under 
the necessity of making a thorough study of the stratigraphy, from the 
basal Mesozoic to the basal Tertiary, inclusive. 
Mr. Hill found that the lower Tertiary and uppermost Cretaceous for¬ 
mations were continuations of nearly similar formations from the adjoin¬ 
ing States, as has been previously supposed, but in addition to those he 
found the lower Cretaceous and probably uppermost Jurassic strata of the 
central Texas region to extend into the State, disappearing near the In¬ 
dian Territory line beneath the later strata of the Mississippi embayment. 
The lowest of the Mesozoic strata he found resting directly upon the 
highly disturbed Carboniferous rocks, and extending from near Antoine 
P. O., Arkansas, to the Brazos river in Texas. Owing to the undoubted 
stratigraphic position of these beneath the lowest marine Cretaceous of 
the Comanche series, and the great resemblance of the fossils therefrom 
to those of the transitional Wealdan and Purbeck beds of Europe, he pro¬ 
visionally referred these to the upper Jurassic* 
The detail^of these beds, together with those of all the overlying strata 
herein mentioned, are in process of publication by the Arkansas State 
Geological Survey. 
Throughout the whole series of strata there were found several non-con¬ 
formities and breaks in faunal continuity, contrary to preconceived ideas, 
indicating many oscillations in depth of the waters in which the forma¬ 
tions were deposited. 
* Science, Jan. 13,1888. 
