The Geology Of The Country Round Blair Atholl Pitlochry And Aberfeldy

Author : George Barrow
Publisher : Theclassics.Us
ISBN 13 : 9781230388359
Total Pages : 78 pages
Book Rating : 4.3/5 (883 download)

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Download or read book The Geology of the Country Round Blair Atholl, Pitlochry, and Aberfeldy; written by George Barrow and published by Theclassics.Us. This book was released on 2013-09 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1905 edition. Excerpt: ... chapter vii. Older Igneous Eocks. Massive epidiorites, coarsely crystalline, showing little and often no foliation, have been met with repeatedly in the Southern Highlands. It has been found that these tend to occur along certain lines, and, when such is the case, these lines are, in Mr. Barrow's opinion, the dominant factor in determining the strike of the folding in the Highland rocks. In the area under description, there are two series of moderately basic intrusions, appearing generally as sills, older than the folding of the Highland schists and always more or less completely metamorphosed. The first and most widespread group occur about the ridge that passes through Ben Vrackie and over a large part of the area south-east thereof; the second are found north-west of this ridge, and, though numerous, the intrusions are often too small to be shown on the map. Mr. Barrow is of opinion that the first series are connected with a number of dyke-like intrusions or feeders that lie along certain lines. That the massive epidiorites were originally ophitic gabbros has been proved in many areas, notably in Glen Fernate, a little to the east in Sheet 56; but traces of this structure can be found in the mass to the north of Ben Vrackie. This is due to the fact that the epidiorites at the summit of that mountain have borne the brunt of the force of the great crushing or schistosity movement and so protected the mass further north. The epidiorite to the east was also affected by this movement, and, though originally a massive rock, shows local crushing. The detailed survey has established the fact that these plutonic intrusions originally passed insensibly into a sill like the sills of hornblende-schist in other parts of the Highlands. G. B....