1895,] Geology and Paleontology. 843 
coincident with its glaciation or not. Aside from the contours of the 
plateaus and valleys, which seem to indicate a fashioning rather by 
meteoric agencies than by pronounced glaciation, the driftless area 
appears to afford the most specific ground for induction. Bearing in 
mind that this is a small area between the present edge of the ice and 
sea-level, which would be overridden easily and completely by an 
advance of the ice-edge of less than five miles, it seems necessary to 
conclude that at the time of the former greater elevation the climatic 
agencies of glaciation could not have been what they are now, but for 
the increased elevation would have caused an extension sufficient to 
overwhelm the driftless area, If it is safe to conclude that elevation 
favors glaciation, then it is necessary to conclude that during any 
period of previous glaciation, there was here no elevation sufficient to 
cause an advance, unless accompanied by counteracting adverse cli- 
matic conditions. The ruggedness of Dalrymple Island bears simi- 
lar testimony. The general angularity of the coastal mountains of 
south Greenland throw the weight of their evidence in the same direc- 
tion. It would appear, therefore, that the former elevation of Green- 
land was not coincident with conditions favoring glaciation.” (Bull. 
Geol. Soc. Am., Vol. 6, 1895.) 
Age of the Sandstones of Crowley’s Ridge.—Crowley’s 
Ridge stretches across north-eastern Arkansas from the Missouri line 
to the Mississippi River at Helena. At numerous localities in this 
ridge a heavy deposit of cherty gravel is exposed in which are small 
(and rarely very large) masses of a compact, fine-grained quartzite. 
The gravel is undoubtedly Plistocene, and, until recently, the sand- 
stones were supposed to be of Paleozoic age. Dr. D. D. Owen referred 
them to the Potsdam from their lithological character. An investiga- 
tion by Mr. R. Ellsworth Call, however, results in the discovery that 
they are indurated sandstones of the same age, and sharing in the com- 
mon history of the gravels through which they protrude, Dr. Branner 
has observed similar facts of metamorphosis in Brazil, and these corro- 
borate the view suggested by Mr. Call that the metamorphism is due to 
weathering. 
The facts ascertained by Mr. Call concerning this disputed formation 
are summed up as follows: 
“ These rocks are of limited occurrence, covering a few hundred acres 
all told ; they are found at rather low elevation in the hills, although 
they sometimes occur as far as the very tops of the highest points in 
the ridge country ; they have yielded fossils of Lower or Eocene Ter- 
