Review of Recent Geological Literature. 315 
REVIEW OF RECENT GEOLOGICAL 
LITERATURE. 
Geologia de los aldredores de Orizaba, con nu perjit de la vertiettte 
oriental de la mesa central. By Dr. Emilio Bose. 410, 52 pp., with two 
plates of photographs of rock exposures and a folded sheet of sections. 
Boletin del Instituto Geologico de Mexico, Num. 13. Mexico. i8gq. 
This paper gives the results of a somewhat detailed study of a small 
area near Orizaba, in the state of Vera Cruz, between i8°3i' and i8°53' 
north latitude, selected on account of its bearmg on the more general 
question cf the structure and origin of the central plateau of Mexico. 
The author combats the current view, advocated especially by Felix 
and Lenk, that the central plateau is bounded on the east, south and 
west by great faults and that its origin is mainly due to them. 
The stratigraphy, which is first discussed, is rather simple, as the 
sedimentary rocks include only three formations, all of which are 
referred to the Cretaceous. As these southern Mexican beds can not 
now be identified with established horizons in either Europe or the 
United States, the Mexican geologists have wisely adopted the plan 
in general use in this country of giving local names to their forma- 
tions. Dr. Bose calls his lowest horizon the Necoxtla slates and these 
ore overlain by the Maltrata limestones and the Escamela limestones. 
The author's views on the age and correlation of these beds will be 
considered later in this review. 
Under the title "structural conditions" a detailed description is 
given of a section of the east slope of the central plateau, following 
in general the course of the Rio Blanco. This emphasizes the intense 
folding oi the lower two members of the Cretaceous section, accom- 
panied by some minor faulting. 
The "hydrographic and orographic part" of the paper consists of 
two brief chapters (3 pp.), in which the author discusses (i) the 
springs and rivers of Orizaba, his description of the many large 
springs near the base of the mountain and of the underground chan- 
nels into which the streams sometimes sink in their upper courses, 
recalling the similar occurrences in Texas; (2) certain valleys and 
basins whose form suggest the work of glaciers, though they must be 
due to some other cause. 
The' foregoing are all preliminary to a discussion of the origin of the 
central plateau of Mexico, in which Bose agrees in general with the 
views of Heilprin and opposes those of Felix and Lenk. The author's 
resume of results obtained is as follows: 
"The mountains of southern Mexico form a structurally homoge- 
neous mass, that is to say an elevation formed by folding. 
"The beginning of the orogenic movement in the west dates from 
the Cenomanian. in the east from the Senonian; hence the western 
part is the more ancient. 
"The princijjal uplift was in the Tertiary, so that the Escamela 
