PETROLOGICAL ABSTRACTS AND REVIEWS 481 



and folding. (4) The time of the intrusion is correlated with that of the 

 Appalachian Revolution. (5) The Kingstown sediments were derived 

 principally from felsite porphyry, micrographic granite, and possibly more 

 basic igneous rocks. 



Albert Johannsen 



Noble, L. F. " Contributions to the Geology of the Grand Canyon, 

 Arizona. The Geology of the Shinumo Area, Pt. I," Am. Jour. 

 Sci., 4th ser., 1910, XXIX, 369-86. 



Describes the Archean rocks (Vishnu) of the area as consisting of a 

 complex of quartz, mica, and hornblende schi?ts, invaded by a batholithic 

 mass of quartz diorite and injected by veins of pegmatite and aplite. These 

 veins are of two ages, the older being folded with the schists, while the 

 younger cut both the schists and the quartz diorite. No attempt is made 

 to work out the general structure of the complex on account of the limited 

 exposures. 



Albert D. Brokaw 



Prior, G. T. "On an Analcite Basalt from Rath Jordan, Co., 

 Limerick," Min. Mag., 1910, XV, 315-17. Figs. 2. 



The rock from Rathjordan has been described by Hull and Alport. 

 According to the latter it is a fine-grained, black basalt which consists of 

 a groundmass of innumerable small grains of augite, magnetite, and amor- 

 phous glass, in which are pseudomorphs of altered olivine and feldspar. 

 The present writer adds that in the supposed glassy groundmass there are 

 also thin needles, probably apatite, and some isotropic material which, 

 under the microscope, resembles leucite. 



A small portion of this isotropic material was isolated and subjected to 

 microscopical and chemical tests. There were strong reactions for sodium 

 while none were obtained for potassium. He concludes, therefore, that 

 most of the supposed leucite is probably analcite. In order to check this 

 conclusion an analysis of the rock was made which appears as follows: 

 SiOa, 40.81; TiO^, 3.86; AUOj, 13.08; Fe203, 6.40; FeO, 7.20; 

 MnO, 0.07; CaO, 10.12; MgO, 10.03; NaaO, 2.43; K2O, 0.31; P2O5, 

 0.88; H2O at iio°C., 0.82; H2O above I io°C., 3.97. The small amount 

 of potash shown by this analysis seems to confirm the above conclusion. 

 The rock is therefore an analcite -basalt. This analysis is compared with 

 one of a leucite basalt from Bohemia, and one of an analcite basalt from 

 Colorado. In the case of the latter rock, Cross argues, that judging from 



