The Quarterly journal of the Geological Society of London . , thespilite is frequently associated with abundant chert, which occupiesthe interstices between the pillows. This is particularly well seen in 1 Q. S. vol. lxviii (1912) p. 76. 106 MR. GARDINER AND PROP. REYNOLDS ON THE [June 1914, the lower part of Two-Stream Valley (see fig. 1, below). Although,as a rule, phenocrysts are seldom observed in a hand-specimen,at the western end of the area, near the Curraghrevagh stream,numerous porphyritic albites occur. {b) The Sedimentary and Pyroclastic Rocks. Although the various rock-types a
The Quarterly journal of the Geological Society of London . , thespilite is frequently associated with abundant chert, which occupiesthe interstices between the pillows. This is particularly well seen in 1 Q. S. vol. lxviii (1912) p. 76. 106 MR. GARDINER AND PROP. REYNOLDS ON THE [June 1914, the lower part of Two-Stream Valley (see fig. 1, below). Although,as a rule, phenocrysts are seldom observed in a hand-specimen,at the western end of the area, near the Curraghrevagh stream,numerous porphyritic albites occur. {b) The Sedimentary and Pyroclastic Rocks. Although the various rock-types are intimately associated, itseems better in describing them to adopt a petrological classificationrather than a geographical one. (1) The Coarse Breccias. As in the Kilbride area, these rocks consist of spilitic andfelsitic breccias, the two kinds of fragments being occasionallyintermingled. Breccias do not cover nearly so extensive an area Fig. 1.—Diagrammatic sketch showing the relations of the tiffs,cherts, and spilites in Two-Stream Valley, T [Approximate scale : 1 inch = 1^ feet.]P= T = Tuff. Cx = Chert in irregular patches. C2= Bedded chert. relatively to the spilites as they do at Kilbride. The large massofJ:breccia seen west of Finny, in the Kilbride area, continuesacross the Finny River into the Lough Nafooey area; but theeastern part of the mass is largely hidden by alluvium, while thewestern part is much interrupted by intrusions of felsite. A bandof coarse breccia, which lies along the southern border of thisfelsite, is easily traceable, owing to its conspicuous consists of angular fragments of a fine-grained felsite weatheringwhite, and of red and green chert, enclosed in a green matrix. Itresembles very closely the band of breccia associated with theDidymograpUis-extensus Shales seen on the southern slopes of Vol. 70.] ORDOVICIAX AXD SILTIEIAX OF LOUGH XAFOOEY. 107 (Ireenaun in the Glensaul district. The he of the breccias them-s
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Keywords: ., bookcentury1800, bookdecade1840, bookidquarte, booksubjectgeology
