Excursion to Mount Sorrel, Buddon Wood, etc. (Charnwood Forest). Thursday. August 29th, 1912 - Geologists' Association excursion

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Geologists' Association Circular No. 146. Session 1911–1912. p.8-9

Excursion to Mount Sorrel, Buddon Wood, etc. (Charnwood Forest). Thursday. August 29th, 1912. (Transcription from GA Circular )

DIRECTORS: E. E. LOWE, B.Sc., F.L.S., and F. W. BENNETT, M.D., B Sc.

EXCURSION SECRETARY: A. C. YOUNG, 17, Vicars Hill, Lewisham, S.E.

Leave St. Pancras at 10.5, due Leicester 12.15. Take ordinary cheap return tickets to Leicester. From Leicester continue the journey to Sileby by 12.24 train, due Sileby 12 41. Tickets (Leicester to.Sileby, 5d. each) will be obtained in the train.

Walk (2 miles) by field path to Mount Sorrel. The Mount Sorrel area is most interesting from the petrological point of view, and it is to the petrology of the district that attention will be chiefly directed.

Typical Mount Sorrel granite will be first inspected and described, and suggestions made as to the significance of the departures from the type as they are examined in the course of the day.

In the main quarry at Mount Sorrel is a very striking basic dyke, traversing the quarry in a N.W. to S.E. direction. The surface of contact with the ordinary rock of the quarry is splendidly shown on the south-east side.

In another place acid felsitic veins are seen.

The main mass of granite is full of patches of dark fine-grained rock which have been variously spoken of as segregation masses and inclusions. The evidence for both views will be discussed.

The Keuper Marls are seen in section around the quarry, and on the south side is a mass of dark grey Drift containing Liassic fossils, chalk-flints, etc.

The journey to the north end of Swithland Reservoir has for its object the examination of granite more basic in character than that of Mount Sorrel. Similar rock will be afterwards inspected at Kinchley Hill.

The party will proceed to Brazil Wood, where the granite is seen in contact with what are doubtless Charnian rocks. The latter have been highly altered by contact with the igneous magma, and are seen in the most clear and diagrammatic contortions, The altered rock at this point approaches amicaceous schist in character and is unique in Leicestershire. It is much " slickensided," and excellent examples showing this structure may be collected. Small garnets have also been found in it.

The knoll of what has been called "hornblende diorite," adjoining Brazil Wood, will be inspected if the water is low enough.

Tea at the Griffin Inn about 5.30, price 1s.

The party will return through the grounds of the Swithland Hall to Rothley Station, G.C.R., leaving 6.52, arriving Leicester 7.5 (G.C.R.), and will then return to London by the 7.55 train (Midland Station). Due at St. Pancras 10 p,m. (Restaurant Car on this train).

REFERENCES.

Geol. Survey Map, Sheet 155.

1878. HILL, E., M.A., and BONNEY, T. G., MA., F R.S., in papers on "The Pre-carboniferous Rocks of Charnwood Forest," describe the "Gneiss" of Brazil Wood in Quart. Journ. Geol. Soc., 1877, p. 783, and 1878, p. 224; Mount Sorrel Granite in Quart. Journ. Geol. Soc., p. 218; Felsite Dyke, Mount Sorrel, in Quart. Journ. Geol. Soc., p. 221; Basalt Dyke, Mount Sorrel, in Quart. Journ. Geol. Soc., p. 222; Diorite from Knoll near Brazil Wood, Quart. Journ. Geol. Soc., p. 224.

1876. ALLPORT, S , "On the Rocks of Brazil. Wood, Charnwood Forest." Geol. Mag., p. 480.

1882. BERRY, E. E.—"Analyses of five rocks from the Charnwood Forest District " (includes Mount Sorrel Granite). Quart. Journ. Geol. Soc., p. 167.

1895. WATTS, PROFESSOR W. W., M.A. D.Sc., F R.S.—"Notes on some specimens collected in the trench, Brazil Wood, Charnwood Forest." Trans. Leic. Lit. & Phil. Soc., July 1895, p. 12.

1603. FOX-STRANGWAYS, C., F.G.S.—"The Geology of the Country near Leicester." Geol. Survey Memoir, No. 156, 1603, p. 7. Geology in the Field, part iv, pp. 777–785. Price 4s;

1904. RASTALL, R. H., HA., F.G.S.—"On basic patches in the Mount Sorrel Granite." Geol. Mag., p. 501.

1907. WATTS, PROFESSOR W. W., M A., D.SC., F.R.S.—"The Pre-Cambrian Rocks of Leicestershire." British Assoc. Guide to Leicester and;District, 1907. (N.B.—The Geological, portion of this Guide may be purchased from Mr. E. Masters, B.Sc., F.G.S., 186, Hinckley Road, Leicester, price 7d., post free.)

Images

Excursion to Mount Sorrel, August 29th 1912

List of photographs

Excursion to Mount Sorrel, August 29th 1912

Page 137 P805594 Kinchley Hill. Quarry in quartz-diorite veined with a fine grained pinkish buff micropegmatite. Excursion to Mount Sorrel, August 29th 1912.
Page 137 P805595 Views from Mount Sorrel showing flooded state of the country. Excursion to Mount Sorrel, August 29th 1912.
Page 137 P805596 Views from Mount Sorrel showing flooded state of the country. Excursion to Mount Sorrel, August 29th 1912.
Page 139 P805597 Granite Quarry at Mount Sorrel. This is a hornblendic granite, grey or pink in colour and not unlike the Eskdale granite in character and composition. Excursion to Mount Sorrel, August 29th 1912.
Page 139 P805598 Granite Quarry at Mount Sorrel. This is a hornblendic granite, grey or pink in colour and not unlike the Eskdale granite in character and composition. Excursion to Mount Sorrel, August 29th 1912.
Page 139 P805599 Granite Quarry at Mount Sorrel. The age of the granite is considered to be the same as that of the Lake District and of south Scotland, viz. Devonian. Excursion to Mount Sorrel, August 29th 1912.
Page 141 P805600 Joints in granite, Mount Sorrel. Excursion to Mount Sorrel, August 29th 1912.
Page 141 P805601 Mount Sorrel granite pierced by dyke of felsite. Excursion to Mount Sorrel, August 29th 1912. [Lines drawn to indicate dyke.].
Page 141 P805602 Brazil Wood. Contortions in Charnian rocks due to an intrusive granite dyke. Excursion to Mount Sorrel, August 29th 1912.
Page 141 P805603 Brazil Wood. Slickensided Charnian mica schist from junction of Precambrian schist and granite. Excursion to Mount Sorrel, August 29th 1912.