200 The American Geologist: March, i8!k» 
relalion to the fertility of the soil in the "blue grass" region. There 
is a good discussion of the soils and in the tabular statement at the 
close of the sketch an excellent resume of all the leading facts oi 
geology presented in the text. 
The London Folio. — Folio 47, just received, follows the Richmond 
folio in series. The cjuadrangle joins the Richmond quadrangle on 
the south. The area embraced is 950.4 square miles. Topography and 
geology are by the same persons as the preceding. On account of the 
similarity in geologic features, much of the description appearing in 
the former folio is applicable here and is repeated. The same general 
interpretation of topography is here adhered to, but the introduction 
of a "structural plain" intermediate in hight and age between the Cre- 
taceous and Eocene peneplains might be looked at in the light of a con- 
cession to a growing opposition in the minds of geologists to the the- 
ory of a multiplicity of peneplains. 
The age of the Cincinnati uplift 's discussed and the conflicting opin- 
ions preserted, but no positive opinions of the author are advanced 
except that land surface must have existed in this region at the end of 
Silurian and again at the end of Lower Carboniferous time. The evi- 
dence in favor of the existence of these late Silurian and early Carbon- 
iferous "Cincinnati islands" is cited, and the possibility of their re 
sumbergence during late Carboniferous time is deemed not unlikely. 
The geological range of formations is not so great as in the Rich- 
mond quadrangle. The series commences with the Panola Formation 
in the Upper Silurian and ends with the Breathitt in the lower Coal 
Measures. The Silurian and Devonian areas are limited to a small out- 
crop in the extreme northwestern corner of the quadrangle. Coal 
Measure strata form two-thirds of the surface outcrop. Taken as a 
whole the region is strictly non-agricultural, the soils being thin and 
poor and the country rugged. There are some commercial coal mines 
in the eastern part of the area. Probably the most interesting contri- 
bution to stratigraphic geology is the determination of the existence of 
two conglomerates in this region: — "the Rockcastle and Corbin con- 
glomerate lentils." Attention is called to a fine instance of an ero- 
sion channel (contemporaneous erosion?) through Pennington shale 
into Newman limestone, which has been filled by gravel of Rockcastle 
conglomerate lentil age. Its existence is made to support the view of 
an erosion interval at the close of Lower Carboniferous time. 
The sketch closes with a resume of the chief facts of the geology 
presented in the usual tabular form, in which also the Kentucky survey 
equivalents for the new names proposed are given. A. M. M. 
