208 
lie in basins of moderate depth, and the 
strata along their southern limb are sharply 
folded and overthrust. The progress of the 
work is such that the McAlester folio will 
probably appear during this fiscal year. 
Among the observations of scientific inter- 
est is the determination of strata of prob- 
able Silurian age in sandstones previously 
considered to be Carboniferous. In the 
19th Annual there is an article entitled 
“ The Geology of the McAlester-Lehigh Coal 
Field,’ by J. A. Taff. 
The geology of Texas is associated with 
the name of Robert T. Hill. Under his di- 
rection a large map. has been prepared of 
the State on the scale of 25 miles to the 
inch, including portions of Oklahoma, and 
an account of the physical geography has 
been written to accompany it. This will 
appear as a folio of the Topographic Atlas 
of the United States, coordinate with the 
folio on physiographic types. ‘The Geology 
of Black and Grand Prairies, Texas,’ a 
comprehensive discussion of the stratigraphy 
and structure of the Cretaceous and later 
formations, is completed and offered for 
publication, and an article on ‘The Geology 
of Portions of the Edwards Plateau and Rio 
Grande Plain Adjacent to San Antonio, 
Texas,’ by R. T. Hill and T. W. Vaughan, 
appeared in the 18th Annual. 
The Rocky Mountains occupy the atten- 
tion of several parties. There the problems 
of stratigraphy, structure, metamorphism 
and vulcanism make it scarcely possible for 
any one geologist to do justice to the phe- 
nomena of a single area, particularly in the 
present development of special branches of 
geologic research. In the San Juan Moun- 
tains of Colorado surveys have for several 
years been conducted with a degree of care 
and detail which must result in a mass of 
well established fact and afford the founda- 
tion for valuable generalizations. In age 
the formations range from supposed Archean 
to post-Tertiary ; in character they include 
SCIENCE. 
(N.S. Vou. X. No. 242. 
an immense variety of sedimentary and 
igneous types, and in structural relations 
bearing upon the problems of vulcanism and 
orogeny they are of the deepest interest. 
The exposures in the rugged but rarely in- 
accessible heights are very clear, and the 
work is being done on a scale which affords 
opportunity for the elaboration of detail. 
The district offers a definite though com- 
plex problem, and it is being worked out 
according to a systematic plan. The 18th 
Annual contains a preliminary report 
on the mining industries of the Telluride 
quadrangle by C. W. Purington, and the 
Telluride folio by Whitman Cross will 
shortly be issued. 
Among the publications which serve to 
add materially to the available information 
concerning the geology of Colorado are the 
Elmoro, Walsenburg and Spanish Peaks 
folios, the manuscripts for which have re- 
cently been received by the Survey in ac- 
cordance with a contract entered into a 
number of years ago. The area which 
they cover comprises a portion of the plains 
and the foothills of the Rockies and extends 
to the Spanish Peaks, where the phenomena 
of successive intrusions of various types of 
igneous rocks are exceedingly interesting. 
The relations of the eruptives have been 
elaborately worked out and appear to indi- 
cate a genetic sequence of petrographic 
types. 
Although work in the precious metal 
districts is not confined to the Rocky Moun- 
tains, that which has been conducted under 
the general direction of Mr. Emmons may 
most connectedly be introduced here. This 
work is on a much larger scale than that of 
the geologic investigations as a rule, and is 
directed to the solution of problems of de- 
velopment of fissures and distribution and 
occurrence of ores. It involves usually the 
detailed study of an area specially surveyed 
on a large scale, and also the minute in- 
vestigation of all accessible underground 
