378 PETROLOGICAL ABSTRACTS AND REVIEWS 
TYRRELL, G. W. “A Petrographical Sketch of the Carrick Hills, 
Ayrshire,” Trans. Geol. Soc. Glasgow, XV (1913), 64-83, pls. 2. 
Geological description of the upland region on the shore of the Firth 
of Clyde near Ayr. The hills consist of a series of lava flows of Old 
Red Sandstone age, and are composed of extrusive andesites and basalts 
and intrusive dolerites and plagiophyres, the latter term applied to 
plagioclase rocks analogous to the orthoclase-bearing orthophyres. 
TyRRELL, G.W. “The Petrology of Arran,” Geol. Mag., X (1913), 
3057 9- 
Riebeckite-orthophyre or riebeckite-trachyte is described from the 
Holy Isle, near Arran, and crinanites or olivine-analcite-dolerites, from 
Whiting Bay and Dippin. 
TYRRELL, G. W., FERcuson, D., and Grecory, J. W. “The 
Geology of South Georgia,” Geol. Mag., I (1914), 53-64. 
A description of the general geology of the island of South Georgia, 
goo miles southeast of the Falkland Islands. The only igneous rocks 
found were certain crystal tuffs of andesitic, latitic, and trachytic char- 
acter, an intrusive diabase or ophitic gabbro, and a quartz-monzonite- 
porphyry, the latter a fragment picked up from a moraine. 
TyrrRELL, G. W. ‘The Petrology of South Georgia,” Trans. Roy. 
Soc. Edinburgh, L (Part iv), No. 25, 1915, 823-36, pl. 1. 
This is a detailed petrographic description of the sediments and 
igneous rocks mentioned in the above paper. The rock previously 
determined as quartz-monzonite-porphyry is here called granite- 
porphyry. 
Usstnc, N. V. “Geology of the Country around Julianehaab, 
Greenland.” Meddelelser om Grinland, XXXVIII (1911). Pp. 
370, figs. 28, maps and secs. 6, pls. 12, chemical analyses. 
The southern third of Greenland is extremely poor in sedimentary 
rocks, only two small areas of post-Archean sediments being found in 
addition to certain Quaternary loam, sand, and gravel deposits. By a 
comparison with the sediments of northeast Canada, however, the order 
of succession of the various rocks may be inferred: Archean gneisses 
and schists, Algonkian(?) granites, diorites, etc., Devonian plutonic 
