782 REGINALD ALDWORTH DALY 
survey regarded the non-foliated parts as fused parts of a series 
of altered sediments. 
2. The parallel structure ought to be best assumed along the 
contact, because there the essential condition of an appropriate 
viscidity will be assumed within a zone which has a dominant 
trend. Where the interaction effects of more than two cooling 
surfaces meet, as they do in a mass of considerable breadth, 
there is a tendency towards the obliteration of parallelism 
induced in any one zone of chilling at a plane of contact. Con- 
vection currents will further complicate the flow-structure and to 
a greater extent in the hotter core of an intrusive mass than in 
the chilled zone. For these reasons parallelism among the con- 
stituent minerals should be most clearly exhibited along the 
boundaries where the structure-planes of the igneous mass will 
accord in direction with the plane of contact. The central area 
may either lose any incipient foliation or show sudden irregular 
changes of strike and dip of fluxional planes which do exist. In 
other words, wherever else it may appear, the fluxional struc- 
ture is to be looked for chiefly at the margins." 
™ BROGGER (Die Silurischen Etagen 2 und 3; Kristiania, 1882, pp. 325, 326), 
describes the endomorphic zone of contact of his granitic and syenitic eruptives as 
possessing a parallel structure “wodurch gestreifte Gesteine, bisweilen wie echte 
krystallinische Schiefer aussehen. It is parallel to the irregular boundaries of the 
igneous rocks. 
McMahon, Note on the Foliation of the Lizard Gabbro; Geol. Mag., 1887, p. 76. 
BARROIS states that inthe granulites of Morbihan the parallelism is most perfect 
when the contact-line is in the strike of the enclosing strata. In such parallel con- 
tacts, the granulite is apt to change to a “granulite porphyroide, a grands éléments, 
alignés fluidalement.” In “contacts perpendiculaires”’ the rock has an aplitic phase 
in which the crystalline constituents have regular geometric forms. He considers 
that such differences in the intruded granite depend on the country-rock as an agent 
chemically inactive but ‘“‘diversement conducteur de la chaleur et de la pression.” 
Sur les modifications endomorphes des massifs granulitiques du Morbihan ; Comptes 
Rendus, CVI, 1888, p. 428. 
GEIKIE, A., The History of Volcanic Action during the Tertiary Period in the 
British Isles ; Trans. Roy. Soc. Edin., 1888, p. 37. 
BARLOw, On the Contact of the Huronian and Laurentian Rocks North of Lake 
Huron, Am. Geol., VI, 1890, p. 22. 
SMITH, W. H.C., Ann. Rep. Geo. Surv. Canada, 1890-1, map. 
GReEGorRY, J. W., The Waldensian Gneisses and their Place in the Cottian 
