Ea Tb Scie Ce Conservatio

NATURE CONSERVANCY COUNCIL EA TB SCIE CE CONSERVATIO No. 21 March 1984 CONTENTS PAGE Glen Roy 3 South Elmsall Quarry 9 National Stone Centre 11 Record of the Rocks 17 Public Inquiries 23 Major Casework 28 Field Facilities 36 Conservation News 43 New Dinosaur Remains 46 Carbonift>rous Suh-Commission 47 Visits to Working Quarries 48 The Geology and Physiography Section, Foxhold House, Thornford Road, Crookham Common, Newbury, Berkshire RGl5 8EL The Geological Conservation Review Unit, Pearl House, Bartholomew Street, Newbury, Berkshire RGI4 5LS PUBLICATIONS OF THE GEOLOGY AND 1. GLENROY PHYSIOGRAPHY SECTION INTRODUCTION The following publications are currently available: Glen Roy is one ofthe most famous landform landmarks in the British Isles. It is Wren's.NesINNR Geologzcal Trail (revised 1974) 15p internationally recognised as a classic geomorphological loc:ality for the Parallel Wren's Nest NNR Geologlcal Handbook (1978) 20p Roads, a series of ice-dammed lake shorelines formed during the Late Pleistocene. FYlleld Down .N.NR Student Worksheets (per set) lOp First documented by Thomas Pennant in 1771, Glen Roy has been the subject of Glen Roy N.NR Th.e Parallel Roads ofGlen RD.}' (1977) 15p over seventy scientific papers and is widely quoted in texts on physical geology and Morlimer Forest Geological Trail (1977) 15p geomorphology. The Parallel Roads, however, are not merely a scientific curiosity; T erlia,), Igneous Rocks of Rhum (1979) 60p they are also regarded as a "natural wonder", As such, their story is rooted in local Staple Edge Geology Teaching Trail (1981) 60p culture and legend concerning the mythical Gaelic hero, Fingal. In the 19th century 'tapl.e Edge Wo,ksheets (per set) 15p their fame enticed eminent travellers and scientists to the area, including Charles Sal/hill Quarry Geological Trail (1982) 75p Darwin and Louis Agassiz. In more recent times Glen Ray is a noted attraction for Inverpol(J' J'{'VR Knockan CliffGeological Trail (1983) 30p visitors to Lochaber, both for its scenic impact and for the striking demonstration it provides of the imprint of the Pleistocene Ice Ages on tbe landscape of Scotland. To be published in May 1984: Geological Guide to Alternative Localities in the East Mendips THE PARALLEL ROADS AND RELATED FEATURES For publications sent by post, the NCC standard rates should be added; these are at The first published description ofthe Parallel Roads was by Thomas Pennant in present: 1771 in his work A Tour in Scotland. 1769. Although bad weather prevented him from For orders up to SOp please add 25p from £10 to £14.99 please add £2.00 visiting what he ealled the "celebrated parallel roads", be noted the local beliefthat from SIp to 99p please add 40p £15 to £19.99 please add £2.75 they had been constructed to facilitate hunting, a view later echocd by Rev. Thomas £1 to £2.99 please add 75p [20 to £24.99 please add [3.50 Ross in the Old Statis/ical Account. According to Ross (1796) the roads. or the "Casan" [3 to £4.99 please add £1.00 £25 and over 10% of order as they were known locally, were "oneofthe most stupendous monuments ofhuman £5 to £9.99 please add £1.50 industry" (p. 549). Local tradition held tbat they were built either by the Kings of Scotland when they resided in the Castle at Inverlochy, about eleven miles from Glen Roy, or by the Gaelic mythical hero, Fingal, and his followers. In support ofthe latter explanation Ross noted that the features were locally called "Fingalian roads". By the early 19th century the Parallel Roads were variously "explained" in the scientific literature as aqueducts for irrigation, diluvial shorelines, marine shorelines or shorelines of debris-dammed lakes. The marine school initially found strong proponents in both Charles Darwin and Charles LycJl. The former, in particular, was deeply impressed by Glen Roy. On 9th August 1838 he wrote to Lyell, "I wandered ovlf the mountains in all directions and examined that most The Geology and Physiography Section and the extraordinary district. I think without any exception, not even the first volcanic Geological Conservation Review Unit of the Nature island, the first elevated beach, or the passage ofthe Cordillera, was so interesting to Conservancy COlUlcil would like to thank all those me as this week. It is far the most remarkable area I ever examined... , 1 can assure who caIne to their aid in promoting earth science you Glen Roy has astonished me" (Darwin, 1887, p. 293). At that time Darwin was conservation through safeguarding, Inaintaining in favour ofa marine origin for the Parallel Roads. It was only 23 years later, in 1861, and iInproving the educational and research field facilities of Britain. that he recanted this belief and accepted the fact that the Roads represented the shores ofa glacial lake. However, it was Louis Agassiz (1840, 1842), a pre-eminent figure in the development of the glacial theory in Britain, who first identified the imprint of glacier ice and propounded the existence offarmer ice-dammed lakes in The opinions expressed by the contributors to Earth Science Consermtion are not Glen Roy, following a visit there in 1840 with William Buckland. This idea was necessarily those of the Nature Conservancy Council. subsequently elaborated by T.F. Jamieson (1863, 1892) in what was to be the ISSN 0142-2324 definitive work on the area for over a century. NIore recently, in a series of papers 3 • based on detailed mapping and surveying,j.B. Sissons has refined the explanation of Augustus an extensive spread ofsand and gravel is believed to have been deposited the Parallel Roads and outlined in detail the sequence ofevents in their formation. by the torrent, as is a large gravel deposit in the Beauly Firth at Inverness (Sissons, His work also reveals the Parallel Roads to be part of a remarkable complex of 1981b). Very perceptively, ]amieson (1865) first raised the possibility that gravel glacial, fluvioglacial and glaciolacustrine landforms and sediments extending from deposits in the Inverness area might be related to the final catastrophic drainage of Loch Laggan in the east through Glen Spean, Glen Roy and Glen Gloy to near Fort the Roy and Gloy lakes, although those he possibly had in mind are eskers and William in the west and north-east to the Great Glen, Loch Ness and Inverness. kames. Subsequently there was a period of oscillating lake levels and smaller The formation and distribution of the Parallel Roads have been described in jokulhlaups through the Spean gorge and later through the Lundy gorge. Upon the detail by Sissons (1978). Largely, they are former lake shorelines, although locally abandonment of the latter, drainage shifted back to the northeast, first as a they occur as fluvioglacial terraces. Three main roads occur in Glen Roy at average 'okulhlaup along a now-abandoned waterfall and channel near Glenfintaig House altitudes of 350, 325 and 260m O.D.; one in Glen Gloy at 355m and one in Glen then via an overspill channel from a later lake in Glen Spean at113m. Considerable Spean at 260m. Typically they are cut in bedrock and comprise an erosional floor fluvial infill took place in Glen Roy and Glen Spean after the drainage ofthe 260m and backslope and a depositional foreslope. Horizontal widths range from 1.6 to lake, and a complexseries ofover twenty terraces has been identified (Sissons, 1979c), 63.6m, and the backing cliff reaches a maximum height of6m (Sissons 1978). To some of which relate to a variety oflower lake levels in Glen Spean and other, later, explain the development of the features, Sissons (1978) invoked a combination of ones to higher levels ofLoch Lochy. Failure ofthe ice dam in Glen Spean led to final wave action and powerful frost disruption of the bedrock along each shoreline. drainage through the Spean gorge, dissection of the valley in.fill and terrace Detailed levelling by Sissons and Cornish (1982a and b) has shown that the shorelines deposition in the Gairlochy area. are not uniformly tilted or warped, and that differential movements have occurred between blocks of the earth's crust. In upper Glen Roy Sissons and Cornish (1983) mapped extensive fans ofcoarse gravel deposited in the lowest lake of the rising sequ~nce. The largest feature is The sequence of events in the formation of the ice-dammed lakes and their associated with outwash from a glacier in Glen Turret. As the lake level rose, the subsequent drainage was summarised by Sissons (1981a), drawing on the details of gravels were mantled with lake sediments (clays and silts), then further gravels as the his earlier papers (Sissons 1977, 1979a, 1979b, 1979c). Lakes in Glen Roy, Glen Gloy lake level fell again. and Glen Spean were impounded by ice of the Loch Lomond Advance from west of Detailed levelling of the Glen Roy shorelines has demonstrated differential the Great Glen coalescing with glaciers from the Ben Nevis range and from the glacio-isostatic uplift of crustal blocks at the start of the Holocene (Sissons and ground to the south via the Laire and Treig breached valleys. Wilson (1900) and Cornish 1983a and b). These dislocations, together with several associated landslips Peacock (1970) established ice movement patterns from striations and the may have been triggered by stresses associated with the Loch Lomond ice advance distributions oferratics, and Sissons (1979a) has mapped and discussed the ice limits and with catastrophic drainage ofthe lakes. The authors point out that this evidence and related landforms which include spectacular lateral moraines, end moraines and challenges some previous assumptions about the form of relict shorelines in areas of hummocky moraine. At its maximum extent the ice reached the western end of the glacio-isostatic uplift and raises questions about crustaI response to loading and present Loch Laggan and penetrated upvalley into Glen Roy and Glen Gloy.

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