Transactions Volume 52 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1905 Excerpt: ...Microgranite.--This rock occurs in two masses, occupying both sides of the lower end of the Vale of St. John. Each of these masses measures about 1 mile from north to south, and from to f mile from east to west; they are each bounded on the east, west and north by Skiddaw Slate, and on the south by the Volcanic Series. It is probable that the fault which separates the two formations may have been the channel through which the mineral matter of these masses, as well as the Uuttermere and Ennerdale Granophyre, welled up from beneath in a molten state. The microgranite consists of orthoclase and microcline-felspar, quartz, calcite and schorl, also some epidote and serpentine: ' part of the last-named has probably replaced mica. The colour is generally grey, but in some places it assumes a reddish tinge. The rock is very much jointed, and frequently contains masses of considerable size that are greatly altered; in some of the joints crystals of galena and blende have been found. Close to the junction with the Skiddaw Slate, the microgranite is slightly altered in appearance and becomes more brittle: the Skiddaw Slate is also hardened, and contains irony spots. Iffvcoux Rocks of Carroek Fell--On Carrock and the adjoining mountain. Great Lingy, there is a series of igneous rocks, consisting of a) granophyre. (h) gabbru. and (c) diabase. The granophyre is a coarsely grained rock, very hard and tough, and of a pale red or brownish-grey colour, with a number of greenish crystals, which show a spherulitio structure, scattered through it. The gabbro is generally coarsely crystalline, but sometimes fine-grained. The base of this rock consists of large crystals of opaque white felspar (plagioclase) and interstitial quartz; and through it are scattered crystals of dark ol...