310 Recent Fuhlications. 
On the production of secondary minerals at sliear-zones in the crystalline 
rocks of the Malvern Hills. By Ciiaklks Callaway. (Quart. Jour. 
Geol. Soc. August 1889.) 
Dr. Callaway starts out with the proposition that the questions are 
to be settled rather by field evidence than by microscopic study, and 
asserts that the chief results were decided in the mind of the writer be- 
fore a single slide had been cut." Nevertheless 150 were cut and sub- 
mitted to Dr. H. B. Patton, Rosenbusch's assistant. When the recon- 
struction of the rock has been complete the shear planes are frequently 
indicated by lines of mica. 
Although disclaiming micro-petrography as a necessary adjunct to 
this study the author hardly gets away from it during the entire 
length of his very interesting paper. His summary is 
1. All the crystalline rocks of the Malvern chain are of igneous 
origin. 
2. The genisses and schists are i^roduced out of igneous rocks by 
secondary action. 
3. The chief mineral and chemical changes have taken place in bands 
of rock (shear zones),which have been subjected to a shearing move- 
ment so that the metamphorism may be described as "zonal." The 
maximum of alteration has been produced in diorite which has been 
sheared in proximity to granite viens. Contact effects are here com- 
bined with dynamic metamorphism. 
4. The most important chemical changes are the removal of the 
bases and the combination of potash with some of the constituents of 
diorite. 
5. The chief mineral changes are the reconstruction of feldspar, and 
the production of biotite (from chlorite) white mica (from orthoclase 
pla^ioclase, black mica and chlorite) granular (juartz, sphene and 
actinolite. 
RECENT PUBLICATIONS. 
1 . State and Government reports. 
Annual report of the Geological Survey of Pennsylvania, for 1887. 
Contains : Cave fossils, (2 plates), by Joseph Leidv ; Fossil tracks in 
the Trias, in York county, Pa., by Atreus Wanner, with eleven 
plates; Report on the New Boston and Morea coal lands (Geological 
and topographical map), by Benjamin Smith Lyman, and The state line 
serpentine and associated I'ocks, by Frederick D. Chester. 
The seventeenth annual report of the Geological and Natural History 
Survey of Minnesota. 8vo. 273 pp. N. H. Winchell, State Geologist. 
Minneapolis, 1889. Contains also reports by H. V. AVinchell and Ulv. 
S. Grant, and a list of American publications since 1872 pertaining to 
the crystalline rocks. 
Natural gas in Minnesota. By N. H. Wixchbll. Bulletin No. 5, 
of the Minnesota survey, pp. 39. 1889. 
