32 
PENNSYLVANIA ANORTHOSITES 
and others. Rocks composed exclusively of feldspar are re¬ 
ported by Duparo and Pearce from the region of Mount Kos- 
winsky in the northern Urals. In Egypt, anorthosite was found 
in place by Newbold,^^ in a mountainous region of the Nile River, 
where it is thought to bear the same relation to the surrounding 
rocks as does the anorthosite in Canada. This rock is described - 
by Sir William Dawson in his “Notes on useful and ornamental 
stones of ancient Egypt.” Lacroix describes briefly anorthosite 
from the Massif central of Madagascar. Among the basic non- 
volcanic rocks is a gabbroic series in which is found “dans le 
Betsiriry (Telomito, a Test de Miandrivazo) . . . associe a 
des gabbros a facies pegmatique, une anorthosite a gros elements, 
exclusivement formee de labrador. Dans la region d’Antanimaro 
(Androy), M. J. Giraud a constate Texistence d’anorthosites 
labradoriques, renfermant par place de grands cristaux d’hyper- 
sthene et formant une sorte de pegmatite de norite. Ces types 
interessants semblent etre exceptionnels.” The chemical analysis 
of the anorthosite shows the rock to be very pure (1 * 5 * 4 • 4-5 • 
Labradorose). Anorthosite is reported by Brogger from India.^* 
“Labradorite rock” from the Lizard Peninsula, in Cornwall, is an 
extremely localized facies of gabbro.^° 
Returning to the great occurrences of anorthosite in North 
America: The anorthosite of Eastern Canada covers a large 
part of the provinces of Quebec and Ontario, and is found also 
in New Brunswick and Manitoba; in the northern Adirondacks 
the anorthosite occurs largely in Clinton, Franklin, and Essex 
counties. The Canadian anorthosite is investigated especially by 
Adams; that of the Adirondacks by Emmons, Kemp, Ruedemann, 
Cushing, Miller,^® and others, all of whom have written extensive¬ 
ly on the pre-Cambrian intrusives. Recently, the theoretical dis¬ 
cussion of the origin of anorthosite is stimulated by Bowen’s 
papers on “The Later Stages in the Evolution of Igneous Rocks,”^^ 
written in 1915, and followed two years later by “The Problem 
of the Anorthosites.” In these papers Bowen supplies data 
20 Mem. Soc. de Physique et d’Hist. Nat. Geneve, T. XXXIV, 1902. ^ 
21 Geol. Surv. Canada, Ann. Kept., new ser., Vol. VIII, pt. J, p. 133, 1895. 
22 Trans. Victoria Inst., London, 1891. 
23 Compt. Rend, des seances de I’Acad. des Sci. Inst, de France, T. 159, 1914. 
24 Die Eruptivgesteine des Kristianiagebietes, Vol. Ill, p. 325, 1898. 
25 Information received verbally from Dr. T. G. Bonney of Cambridge, England. 
26 Bull. Geol. Soc. America, Vol. XXIX, p. 399, 1918. 
27 Journal Geology, Supplement to Vol. XXIII, No. 8, 1915. 
28 Ibid., Vol. XXV, pp. 209-243, 1917. 
