Review of Recent Geological Literature. 259 
The relation of secular roCk-dismtegration to certain transitional 
crystalline schists. By Raphael Ptjmpelly. Bulletin, G. S. A., vol. ii, 
pp. 209-224, with four figures in the text; Feb. 19, 1891. Pre-Cambrian 
decay of the granitoid gneiss forming the nucleus of Hoosac mountain, 
in western Massachusetts, is shown to have led to the formation of the 
overlying conglomerate and gneiss, laterally continuous into quartzite 
in which Mr. Walcott has found Lower Cambrian trilobites. The depth 
of this ancient rock-decay was probably similar to that now found upon 
all areas of feldspathic rocks in warm and moist regions, where the sur- 
face has not been glaciated. During the folding and metamorphism of 
the Cambrian strata of the Hoosac and Green mountains, there has often 
been produced an apparent transition and conformity with the Archtean 
gneisses and granites. The transition zone consisted below of j that 
part of the more or less disintegrated Archaaan which escaped denuda- 
tion during the subsidence of its land surface into the Cambrian sea, 
and above comprised the basal Cambrian conglomerates and other detri- 
tal beds formed by the erosion of the disintegrated rock. Lithologic 
gradation and parallelism of lamination from Cambrian to Arclnean are 
found in this zone. Analogous observations are cited from the Adiron- 
dacks, the southern Appalachians, and Iron mountain, Missouri. 
Tlic Gcatcctonic and Physiographic Qeology of western Arkansas. By 
Akthtjb Winslow. Bulletin, G. S. A., vol. ii, pp. 225-242, with a map, 
and nine figures in the text ; Feb. 26, 1891. This paper gives a very 
interesting general description of the stratigraphy and contour of a 
Carboniferous area lying on both sides of the Arkansas river and ex- 
tending from Ft. Smith 90 miles eastward. The greater part of the 
district has a nearly horizontal stratification or only gentle flexures. 
South of these are steep flexures, overturned folds, and faults, running 
from east to west, which the author ascribes to the time of the Appa- 
lachian revolution and to "a trans-Mississippian extension of the same 
cause." Following Reade, this cause is thought to be the rise of the 
isogeotherms in a mass of very thick sediments. The resulting expan- 
sion of their lower layers would find room by flexure and plication, with 
upheaval; and during this process superficial erosion would expose 
steeply inclined or compressed and inverted folds, the dips becoming 
steeper and the folds more appressed in proportion as the overlying 
weight diminished. 
Report upon the United States Geographical Surveys west of the one 
hundredth meridian, in charge o/Capt. George M. Wheeler, under the 
direction of the chief of engineers, U. S. Army; vol, i. Geographical 
report, quarto, pp. 780. xxxviii plates and three maps: War Depart- 
ment, Washington, lss'.i. 
This report, though made under dale of .June l. 1879, when it was 
substantially completed, was not offered for publication till 1887, "from 
pressor other duties and subsequent prolonged illness."' Though it is 
the first in the series of seven volumes % of Lieut. Wheeler's survey, it is 
the last to appear. Volume ii, Astronomy and Barometric llypsomotry, 
