92 REVIEWS 
holds that the quartz porphyry and the underlying syenite are essen- 
tially contemporaneous parts of a composite laccolith. It is suggested 
that the heated condition of the syenite at the time of the quartz- 
porphyry intrusion favored notable differentiation by prolonging the 
magmatic life of the later intrusive. 
The origin of the ore inclusions in the porphyry is the crucial point 
in any hypothesis of the origin of the Kiruna ores. Professor Daly’s 
view is a satisfactory interpretation of the field relations; likewise it 
accords best with recent opinion concerning differentiation processes. 
doled ee 182 
Journal of the Washington Academy of Sciences, V, 1915, 687 pages. 
Articles of geologic interest in recent numbers of the Journal are: 
“The Paleozoic Section of the Ray Quadrangle, Ariz.,” by F. L. Ran- 
some; “Factors in the Movement of the Strand Line,” by Joseph 
Barrell; “‘The Calculation of the Calcium Orthosilicate in the Norm of 
Igneous Rocks,” by H. S. Washington; and “The Solubility of Calcite 
in Water in Contact with the Atmosphere, and Its Variation with 
Temperature,” by R. C. Wells. Chase Palmer contributes an article 
on “‘ Bornite as Silver Precipitant.” 
Wel, IR 133, 
Mineral Land Classification in Part of Northwestern Wisconsin. 
By W. O. HorcukIss, assisted by E. F. BEAN and O. W. 
WHEELWRIGHT. Wisconsin Geol. and Nat. Hist. Survey, 
Bull. No. 44, 1915. Pp. 376, pls. 8, figs. 39, maps go. 
This volume constitutes the report on the land classification of 87 
townships in northern Wisconsin. ‘The work was done during the field 
seasons of 1913 and 1914. ‘The object of the survey was “to discover 
the evidence that exists as to the presence or absence of iron-bearing 
rocks, and as to the geologic structure of the region.” The difficulties 
encountered either by the geologist who attempts to unravel the pre- 
Cambrian geology of this heavily drift-covered area, or by those who 
seek to locate iron ores here may be appreciated from the fact that in 
this area of over 2,000,000 acres the total exposed area of rocks of all 
kinds does not exceed 300 acres. Naturally, the report is based largely 
on the comprehensive series of magnetic observations. 
Part I includes chapters treating of the methods of field work, 
general geology of the area covered, magnetic observations, land classi- 
