282 PETROLOGICAL ABSTRACTS AND REVIEWS 
SOBRAL, JOSE M. Contributions to the Geology of ihe Nordingra 
Region. Upsala, 1913. Pp. 178, pls. 12, map 1, fig. 1, many 
analyses. 
The rocks of the Nordingra district belong to three different geologic 
epochs. The oldest is composed entirely of igneous rocks—anorthosites, 
gabbros, and granites—and is of most importance. The second group 
consists of Jotnian quartzite and sandstone; the third of more recent 
diabases and monzonites intruding and covering the sandstone. The 
topography of the region is due in part to faults, some of the firths and 
valleys certainly having been caused by dislocations, but the consolida- 
tion of the magma and the composition of the igneous rocks have had the 
greatest effect upon the land forms. 
Analyses are recalculated into the C.I.P.W. and Osann systems. 
A new dike-rock, consisting essentially of albite and augite with 
titanite, magnetite, and apatite, is described and analyzed. The author 
calls it vérnsingite. An analysis is given. 
Somers, Ransom Evarts. “Geology of the Burro Mountains 
Copper District, New Mexico,” Bull. ror, Amer. Inst. Min. 
Eng., 1915, 957-96, figs. 25. 
This paper deals chiefly with the economic geology of the region, 
although a few pages are devoted to the general geology and the igneous 
rocks which occur. Among the latter are granite, quartz-porphyry, 
quartz-monzonite, and volcanic breccias. 
SomMMER, MartTIN. “Beitrag sur petrochemischen Kenntnis des 
Lausitzer Granitmassivs,’ Ber. k. sdchs. Gesell. Wiss., 1915. 
Pp. 71, pls. 4, including one map. 
The Lausitz granite area to the east of Dresden consists of twelve 
varieties of granite; a normal granitite, a normal granite, and ten other 
varieties. All but one of these varieties were analyzed, and these, as 
well as a number of older analyses, are given. The molecular percentages 
are computed and the results plotted in Osann’s ACF, SAIF, and AICAIk 
diagrams and in FeCaM, CaNaKk, and M.O; MO M.0 triangles. All of 
these clearly show the relationships between the various granites, for 
the points lie practically along straight lines, or within small circles. 
The relationships between the different rocks are discussed. 
