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Charnwood Forest: A Buried Triassic Landscape Author(s): W. W. Watts Source: The Geographical Journal, Vol. 21, No. 6 (Jun., 1903), pp. 623-633 Published by: geographicalj Stable URL: http://www.jstor.org/stable/1775653 Accessed: 27-06-2016 02:41 UTC Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at http://about.jstor.org/terms JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. The Royal Geographical Society (with the Institute of British Geographers), Wiley are collaborating with JSTOR to digitize, preserve and extend access to The Geographical Journal This content downloaded from 198.91.37.2 on Mon, 27 Jun 2016 02:41:21 UTC All use subject to http://about.jstor.org/terms ( 623 ) CHARNWOOD FOREST: A BURIED TRIASSIC LANDSCAPE." By W. W. WATTS, M.A., M.Sc., F.R.G.S., Sec. G.S., Assistant-Professor of Geology and Physiography at Birmingham University. INTIRODUCTION. CHAlNWOVOD FORIEST is situated in Leicestershire, about 6 miles north-west of Leicester, and 3 miles south-west of Loughborough. It is practically defined by a curved line joining the following villages and hamlets: Woodhouse Eaves, Cropston, Groby, Markfield, Bardon, Whi twick, Thring- stone, Sheepshed, and Nanpantan. Although once famous for its slates, its chief industry now consists in road-metal, paving setts, and artificial flagstones. Some of the land is agricultural, but most of it is devoted to parks and private residences, partly because of its picturesque relief, but partly, also, because the soil is often barren, supporting only moor- land and forest growth, and so can be better given over to hunting and shooting. The land is also utilized for the purposes of water-supply, and as a lung for the towns of Loughlorough and Leicester, and, since the opening of the Great Central Railway, by Nottingham and other towns. CIIARACTER OF TEII LANDSCAP,E The most obvious feature of its landscape is the sharpness of the con- trasts that it presents. While much of the lower ground is flat and monotonous, with a good soil, fertile and occupied by farms and gardens, the hills are sharp and stony, with a pcor soil and a scanty vege- tation; they frequently culminate in a crag or ridge with abrupt sides and a narrow crest ; indeed, the walls of the crags, although of no great height, are sometimes vertical and occasionally even overhanging. Fig. 1 shows a hill with several crags, separated by a pastoral fiat from a second craggy hill, from which the view was taken Again, while most of the valleys have soft and rounded contours, with alluvial flats and marshes, there are a few which are winding and gorge-like, wit[l flanks of steep and bare rock, and with the streams running over rocky beds. Other characteristic features of the landscape will be pointed out later on. THE Two RocK TYPES. The sharp contrasts above alluded to at once suggest to the geologist abrupt contacts of two very different classes of rock, and the examina- ti,on of the numerous sections soon proves that this surmise is correct. 'The bolder scenery is found to be based on hardened and ancient Charnian rocks of pre-Cambrian age, principally volcanic in origin; the milder landscape is based on the Keuper Marl of the Triassic * Read at the Royal Geographical Society, 31arch 9, 1903. Map, p. 700. 2 T 2 This content downloaded from 198.91.37.2 on Mon, 27 Jun 2016 02:41:21 UTC All use subject to http://about.jstor.org/terms 624 CHARNWOOD FOREST: A BURIED TRIASSIC LANDSCAPE. System, which has long been known to rest unconformably on the older rocks. The woods, crags, and higher grounds in Fig. 2 are situated on Charnian rocks, the lower ground on the Keuper Marl. The ancient rocks are of several types, but the dominant one is a bedded series of fine and coarser volcanic tuffs interbanded with coarse agglomerates and breccias, and passing up into conglomerates and slates (see Figs. 4, 5, and 7). These rocks are folded into an ellip- tical dome the long axis of which points north-west and south-east, but only the southern half of this structure is anywhere exposed. The rocks are cut by faults, jointed, and cleaved, and there have been intruded into them three or four different kinds of igneous rocks, in- cluding " porphyroids," syenites, and granites. Sometimes these are in small dykes or bosses, but at Peldar and High Sharpley (see Fig. 8), at Bradgate Park, Groby, and Markfield, and at Mount Sorrel (see Fig. 12), the masses are of considerable size, their outcrops measuring from half a square mile to nearly a square mile in area. It is these igneous rocks which are chiefly quarried for road-metal. All the rocks are much hardened by pressure, silicification, or the formation of epidote, and as a consequence there is comparatively little differential weathering or denudation along stronger or weaker kinds. On the whole the rocks of the lowest and highest divisions are relatively weaker, while the middle division is the one which tends to stand out in a broken horseshoe of hills. The newer or Triassic rooks belong to the upper or Keuper division of that formation. Only in the north is the Keuper Sandstone visible; if it occurs further south, it is so far underground that it has never yet been seen. The dominant covering rock in the rest of the area is the Keuper Marl or New Red Marl-a soft red clay of considerable thickness (see Fig. 3). Its basement beds, when they are seen to rest on the ancient rocks, contain a small thickness of breccia, the angular blocks having been derived from the (harnian rocks leneath; but this is rarely of any thickness. A few bands of greenish sandstone, locally called " skerry," occur here and there, generally made up of material broken from the Charnian rocks. Fig. 3, taken at Croft Hill, south- west of Charnwood Forest, shows the relation of the Keuper MIarl, with its green bands, to the Charnian rocks beneath, and it also shows the basal breccias made of angular fragments denuded from the underlying series. UNCONFORMABLE RELATIONS OF TIIE ROCKS. Thuis a county in which the landscape reminds one of patches of \\ales planted a-mongst the level pastoral country of the Midlands is proved by geological examination to be really a landscape of Welsh type submerged under the New Red Marl, the dominant rock of the Englislh Midlands. Further examination shows that the cover is in many places a thick one, and that the ancient rocks are for the most This content downloaded from 198.91.37.2 on Mon, 27 Jun 2016 02:41:21 UTC All use subject to http://about.jstor.org/terms FIG. 1. The Hanging Rocks, Beaumanor Park, Woodhouse Eaves; looking S.E. FIG. 2. Bradgate Park; Crags of Charnian Rock rising from flat Triassic ground. This content downloaded from 198.91.37.2 on Mon, 27 Jun 2016 02:41:21 UTC All use subject to http://about.jstor.org/terms FIG. 3. Croft Quarries; Keuper Marls and Breccias resting unconformably on Syenite. Taken by permission from a photograph by Messrs. J. Burton & Sons, of Leicester. FIG. 4. The Hanging Rocks, Beaumanor Park; looking N.W. From a photograph by Mr. F. R. Rowley, of the Town Museum, Exeter. This content downloaded from 198.91.37.2 on Mon, 27 Jun 2016 02:41:21 UTC All use subject to http://about.jstor.org/terms CHARNWOOD FOREST: A BURIED TRIASSIC LANDSCAPE. 625 part so deeply buried that only their highest points protrude through it. It has already been pointed out that the protruding parts are steep and mountain-like (see Fig. 4). Observations in the visible sections prove that these steep slopes are continued under the cover, and this is in accord with the experience of the quarry-owners in their attempts to obtain rock beyond the limits of the actual outcrop. It is speedily found that the amount of waste cover (New Red Marl) to be removed renders it too expensive to attempt to win the rock far from its visible outcrop. Records of well-sections collected by Mr. Fox-Strangways give further proof, for wells have been sunk a few yards away from the visible outcrop of the ancient rock without reaching that rock at a depth of many feet. Thus the New Red Marl is actually covering a mountain system of which the summits alone are visible, while the flanks and intervening valleys are for the most part buried and filled up with the newer formation. Areas like the granite knobs of Mount Sorrel, the copse- clad crags of Bradgate Park (see Fig. 2), or the isolated rooks in the centre of the Forest about the headwaters of the Blackbrook, give examples of innumerable summits, from a tenth of a square mile to a hundred square yards and less in area, standing forth like islands from a sea of MTarl. The more important ridge of Bardon Hill, the highest summit in the Forest, is closely cloaked with the Red Marl, which rises over 800 feet on its flanks. And the three much greater masses, the first extending from Peldar Tor to Grace Dieu, the second includ- ing the Outwoods, Beacon Hill, and Broombriggs, and the third the central massif round Benscliffe, while flanked with Marl to varying heights, push out many summits, shoulders, and buttresses, as well as the flanks which intervene, through the cloak.

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