Petrological Abstracts and Reviews 



ALBERT JOHANNSEN 



Miller, Willl^m J. " Geology of the Blue Mountain, New York, 

 Quadrangle," Bull. ig2, N. Y. State Mus., 1916 (191 7). 'Pp. 68, 

 map I, pis. II, fig. I. 



The Blue Mountain Quadrangle in the Adirondack region lies in northern 

 Hamilton County, N. Y. From oldest to youngest, the formations are: the 

 Grenville series, limestones, and quartzites, followed by two small intrusions 

 of anorthosite. The most widespread rocks of the region are syenite and 

 granite with basic phases which are intrusive into both the GrenviUe series and 

 the anorthosite. Following this came gabbro, still later pegmatite and a few 

 dikes of diabase. Glacial and postglacial deposits complete the series. The 

 rocks of the Grenville series are thought to be sedimentary. Twelve quartz- 

 syenites are described, three of which are said to be "practically monzonites." 

 The quartz ranges from 12 to 20 per cent, consequently the reviewer would 

 prefer not to call them quartz-syenites, which name he would limit to syenites 

 with less than 5 per cent quartz, but granites. In the reviewer's system ten of 

 these rocks are classed in 226', granites (or in limited sense monzo-granites), 

 the remaining two are 226" or quartz-monzonites. The basic phases of the 

 syenite are 228, 328, 227", 2212, 3211', tonalites, quartz-monzonite, diorite, 

 and monzo-diorite. Of fifteen granitic-syenites and granites, thirteen are 226' 

 (granites), one 126' (a leuco-granite), and one near Daly's Moyie sUl rock, at 

 the intersection of Families i, 2, 5, and 6', in Class 2, Order 2. Of six "typical 

 gabbros," one (No. 17) is a garnet-bearing melagabbro, and one (No. 52) is a 

 garnet-bearing norite. The other four are said to contain oligoclase-labrador- 

 ite and andesine-labradorite which, without further descriptions of the feld- 

 spars, prevents their classification. 



Miller, William J. "Adirondack Anorthosite," Bull. Geol. Soc. 

 Amer., XXIX (1918), 399-462, figs. 3. 



Miller takes exception to Bowen's statement (Jotir. Geol., XXV [1917], 

 242) that " Anorthosites are made up almost exclusively of the single mineral 

 plagioclase." Bowen's statement is and is not true, depending upon whether 

 the rock anorthosite or the anorthosite formation is meant. Hunt's original 

 definition applied to a whole series of rocks which are " composed chiefly of a 

 lime-soda feldspar, varying in composition from andesine to anorthite, and 



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