Other editions - View all
abundant amphibolite angle anticline antigorite appears augite bands boulders brachiopods calcite Cambrian Carboniferous cent centimetres Chalk character chert clay cleavage Colonsay conglomerate Cyathaxonia-Beds David's deposits described diameter district Dolhir Drift dykes east enstatite evidence exposed exposures Farnham fault feet felspar fine-grained folding fossils fragments Geol Geological glacial beds Glyn gneiss grains granite granophyre gravel Grit Hill horizon hornblende igneous inches intrusion Journ junction lamprophyre limestone Lithostrotion Llandovery locality Loughshinny lower M'Coy margin mass material Metriorhynchus miles millimetres mineral Miocene monoclinic numerous occur olivine origin Orthis outcrop paper Pebidian phyllite plane PLATE portion present probably Productus Prof pyroxene quarry quartz quartzites ridge River rocks sand sandstone schists seen serpentine shales shown side slates species specimens Spirifer stream structure subzone surface Surv Thayetmyo thickness tuffs upper valley Wenlock zone
Page 140 - In Logan's original classification of the Laurentian this term — apart from the Upper Laurentian which was proved to be composed essentially of anorthosite intrusions — included two series differing in character, namely, the Lower Orthoclase (Fundamental Gneiss) and the Grenville series. Now that investigations have shown that these two series differ in origin, one being essentially a great development of very ancient sediments, and the other consisting of great bodies of igneous rock intruded...
Page 126 - Towards the north-west, however, the granite, in ever-increasing amount, arches up the sedimentary series and wells up through it, in places disintegrating it into a breccia composed of shreds and patches of the invaded rock scattered through the invading granite, until eventually connected areas of the sedimentary series disappear entirely and over hundreds of square miles the granite and granite-gneiss alone are seen, holding, however, in almost every exposure, inclusions which represent the last...
Page 134 - Certain granular amphibolites represent altered igneous intrusions, for they are found in the form of dykes cutting across the stratified white crystalline limestone, on the shores of Jack's Lake in the township of Methuen. The limestones here dip at a low angle to the south, and are excellently exposed in the form of low cliffs about the side of the lake.
Page cxi - Balk will, who has filled the office of honorary treasurer for the last nine years and has now found himself unable to continue in the position. His books have been kept with great neatness and accuracy, and his attention to the business of the Society has always been prompt and...
Page 663 - ... to accompany the medal, the remaining interest to be given in one or more portions, at the discretion of the council, for the encouragement of geology or of any of the allied sciences by which they shall consider geology to have been most materially advanced, either for travelling expenses or for a memoir or paper published or in progress, and without reference to the sex or nationality of the author or the language in which any such memoir or paper may be written.
Page 133 - These amphibolites are not peculiar to this area, but occur abundantly everywhere in the Laurentian. They have always proved to be one of the chief difficulties in the way of a correct understanding of the geology of this system, seeing that it has been impossible to do more than indulge in conjectures concerning their origin. The same difficulty has been...
Page 663 - as an acknowledgment of eminent services in any department of Geology, irrespective of the receiver's country ; but he must not be older than 45 years at his last birthday, thus probably not too old for further work, and not too young to have done much.
Page 134 - I remarkable convergence of type, whereby rocks of widely different origin come to assume identity of character, explains the difficulty which has been experienced up to the present time in arriving at a satisfactory conclusion concerning their genetic relations. (a) Some of these amphibolites result from the metamorphism and recrystallization of sediments. To this class belong the feather-amphibolites above described, which usually occur in thin bands alternating with crystalline limestone, and...
Page 142 - ... however, probably developed only a small part of the space which the granite now occupies ; (5) the invading granite not only exerted a mechanical action upon the invaded strata, but also gave rise to a variety of metamorphic products, among others amphibolite produced by its action in the limestone, which accounts for the fact that while the invaded strata are chiefly limestone, the fragments of the latter, where found in the granite, consist of amphibolite ; (6) the invading bathyliths...
Page 142 - The granite-gneiss of the bathyliths not only arched up the invaded strata into a series of domes, but ' stoped ' out portions of the sides and lower surface of the arches, the fragments torn off from walls and roof by the invading granite being found scattered throughout the mass of the invading rock : this