Hartfell Score - an excursion: Difference between revisions
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A visit to Hartfell Score involves 5 to 6 km of easy walking on the public footpath. Warm and waterproof clothing is desirable in view of the exposed nature of the terrain. | A visit to Hartfell Score involves 5 to 6 km of easy walking on the public footpath. Warm and waterproof clothing is desirable in view of the exposed nature of the terrain. | ||
Hartfell Score is one of the largest exposures in the Moffat Shale of southern Scotland, and is the type area for Lapworth's Hartfell Shales division of the Moffat Shales. The exposure was described in some detail by Lapworth (1878, pp. 292-296) and Peach & Horne (1899, pp. 134-137). | Hartfell Score is one of the largest exposures in the Moffat Shale of southern Scotland, and is the type area for Lapworth's Hartfell Shales division of the Moffat Shales. The exposure was described in some detail by Lapworth (1878, pp. 292-296)<ref>Lapworth, C. 1878. The Moffat Series. Quart. J. Geol. Soc. Lond. 34, 240-346. Lapworth, C. and Wilson, J.1870. The Lower Silurian rocks in the neighbourhood of Galashiels. Trans. Edinb. Geol. Soc. 2, 46-48.</ref> and Peach & Horne (1899, pp. 134-137)<ref>Peach, B.N. and Horne, J. 1899. The Silurian rocks of Britain, 1, Scotland. Mem. Geol. Surv. U.K. | ||
From the centre of Moffat head north on the road to Edinburgh (A701), but after about 400 m, near the church, where the main road swings left out of the town, take the minor road (a dead end) that continues northwards to Ericstane (Figure 43). After 5 km the road crosses Auchencat Burn; here there is limited parking space by a large red corrugated iron building south of the bridge. Just north of the bridge a public footpath is signposted eastwards to Hartfell Spa; the way is marked by the occasional confidence-post. The path follows Auchencat Bum upstream, but lies well above the north bank. Bluffs by the burn show the brick-red colour of the Permian rocks that floor the valley of the River Annan. After nearly a km there is a hill-fort, from which one can see, to the north-east, the gash in the hill that is Hartfell Score (NT 097 117). North-west of the hill-fort the burn occupies a gorge with a waterfall at the head (Frizles Linn); at this place in the gorge, upfaulted Lower Birkhill Shales are overlaid by Cala greywackes. The path stays high above the burn to the head of Frizles Linn, but just beyond it descends to the bank by a series of well-made steps. The path remains on the north bank and follows roughly the line of the fault that brings up the Hartfell Inlier. Half a km upstream, on the south bank, is the site of a trial for copper minerals, associated with an outcrop of green-stained Birkhill Shales. After a further half km Auchencat Burn swings away to the right, but the path continues north-eastwards, parallel now with a tributary, the Spa Well Burn; and the Hartfell Spa itself is reached about 1.5 km from the steps. The chalybeate waters of Hartfell Spa were declared beneficial by John Williamson in 1748. The well is now enclosed and sheltered by a small stone building. Just upstream of the spa are large masses of what looks like a conglomerate; this is a fossil scree known as "head" consisting of small fragments and consolidated by a ferruginous cement during the post-glacial period. | From the centre of Moffat head north on the road to Edinburgh (A701), but after about 400 m, near the church, where the main road swings left out of the town, take the minor road (a dead end) that continues northwards to Ericstane (Figure 43). After 5 km the road crosses Auchencat Burn; here there is limited parking space by a large red corrugated iron building south of the bridge. Just north of the bridge a public footpath is signposted eastwards to Hartfell Spa; the way is marked by the occasional confidence-post. The path follows Auchencat Bum upstream, but lies well above the north bank. Bluffs by the burn show the brick-red colour of the Permian rocks that floor the valley of the River Annan. After nearly a km there is a hill-fort, from which one can see, to the north-east, the gash in the hill that is Hartfell Score (NT 097 117). North-west of the hill-fort the burn occupies a gorge with a waterfall at the head (Frizles Linn); at this place in the gorge, upfaulted Lower Birkhill Shales are overlaid by Cala greywackes. The path stays high above the burn to the head of Frizles Linn, but just beyond it descends to the bank by a series of well-made steps. The path remains on the north bank and follows roughly the line of the fault that brings up the Hartfell Inlier. Half a km upstream, on the south bank, is the site of a trial for copper minerals, associated with an outcrop of green-stained Birkhill Shales. After a further half km Auchencat Burn swings away to the right, but the path continues north-eastwards, parallel now with a tributary, the Spa Well Burn; and the Hartfell Spa itself is reached about 1.5 km from the steps. The chalybeate waters of Hartfell Spa were declared beneficial by John Williamson in 1748. The well is now enclosed and sheltered by a small stone building. Just upstream of the spa are large masses of what looks like a conglomerate; this is a fossil scree known as "head" consisting of small fragments and consolidated by a ferruginous cement during the post-glacial period. | ||
An excellent view of the main sector of Hartfell Score | An excellent view of the main sector of Hartfell Score is obtained from a point 100 m or so upstream from the spa. As is frequently the case in the upfaulted inliers of Moffat Shales, the south-east (right-hand) side of the inlier is strongly deformed; at Hartfell this side is composed, at least partly, of Lower and Upper Birkhill Shales, but it is very difficult to interpret the stratigraphy in detail. The north-west side of the exposure, however, is much more coherent. Though complicated by thrusting, the general succession is as follows: | ||
* Upper Hartfell Shales - grey 'barren' mudstones - Ashgill | * Upper Hartfell Shales - grey 'barren' mudstones - Ashgill | ||
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''C. styloideus, C. tubuliferus, Orthograptus amplexicaulis, O. calcaratus basilicus, O. quadrimucronatus, Plegmatograptus nebula'', and other forms. | ''C. styloideus, C. tubuliferus, Orthograptus amplexicaulis, O. calcaratus basilicus, O. quadrimucronatus, Plegmatograptus nebula'', and other forms. | ||
Above the black mudstones of the ''P. linearis'' Zone are pale 'barren' mudstones; it is not known if these are part of the Upper Hartfell Shales. Just south-west of the gullies that gash the Main Cliff at its north-east end they form a small cliff, above which the slope slackens and the exposure is less complete. If these are the Upper Hartfell Shales their full thickness is not seen here, the upper part (including the black ''anceps'' beds) being faulted out; it is possible, however, that black seams with ''Dicellograptus compianatus'', present at Dob's Linn, might be found. | Above the black mudstones of the ''P. linearis'' Zone are pale 'barren' mudstones; it is not known if these are part of the Upper Hartfell Shales. Just south-west of the gullies that gash the Main Cliff at its north-east end they form a small cliff, above which the slope slackens and the exposure is less complete. If these are the Upper Hartfell Shales their full thickness is not seen here, the upper part (including the black ''anceps'' beds) being faulted out; it is possible, however, that black seams with ''Dicellograptus compianatus'', present at Dob's Linn, might be found. | ||
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Higher on the slope the upper part of the Glenkiln Shales reappear, apparently on an upthrust. Here they include black shales that have yielded fragmentary graptolites. Above them lie the lower part of the Lower Hartfell Shales (yielding ''D. clingani'' and ''C. caudatus'') and perhaps also the ''P. linearis'' Zone; and near the top of the exposure the Glenkiln Shales reappear once more, indicating a further thrust slice, the details of which have not been studied. | Higher on the slope the upper part of the Glenkiln Shales reappear, apparently on an upthrust. Here they include black shales that have yielded fragmentary graptolites. Above them lie the lower part of the Lower Hartfell Shales (yielding ''D. clingani'' and ''C. caudatus'') and perhaps also the ''P. linearis'' Zone; and near the top of the exposure the Glenkiln Shales reappear once more, indicating a further thrust slice, the details of which have not been studied. | ||
Despite its importance and the excellent exposure, Hartfell Score remains inadequately studied. The most detailed account of the Main Cliff remains that of Lapworth (1878). No systematic account of the distribution of fossils there has been published, though preliminary results obtained by the Palaeontological Association in 1990 | Despite its importance and the excellent exposure, Hartfell Score remains inadequately studied. The most detailed account of the Main Cliff remains that of Lapworth (1878)<ref>Lapworth, C. 1878. The Moffat Series. Quart. J. Geol. Soc. Lond. 34, 240-346. Lapworth, C. and Wilson, J.1870. The Lower Silurian rocks in the neighbourhood of Galashiels. Trans. Edinb. Geol. Soc. 2, 46-48.</ref>. No systematic account of the distribution of fossils there has been published, though preliminary results obtained by the Palaeontological Association in 1990. | ||
===References=== | |||
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[[Category:6. The South of Scotland]] | |||
Revision as of 21:57, 14 March 2015
By A.W.A. Rushton. From Scottish Borders geology: an excursion guide edited by A.D. McAdam, E.N.K. Clarkson, P. Stone. Edinburgh : Scottish Academic Press (for Edinburgh Geological Society), 1992.
O.S.1:50 000 sheets 78, Nithsdale & Lowther Hills
B.G.S. Scotland 1:50 000 sheet 16 (Moffat)
A visit to Hartfell Score involves 5 to 6 km of easy walking on the public footpath. Warm and waterproof clothing is desirable in view of the exposed nature of the terrain.
Hartfell Score is one of the largest exposures in the Moffat Shale of southern Scotland, and is the type area for Lapworth's Hartfell Shales division of the Moffat Shales. The exposure was described in some detail by Lapworth (1878, pp. 292-296)[1] and Peach & Horne (1899, pp. 134-137)Cite error: Closing </ref> missing for <ref> tag. No systematic account of the distribution of fossils there has been published, though preliminary results obtained by the Palaeontological Association in 1990.
References
- ↑ Lapworth, C. 1878. The Moffat Series. Quart. J. Geol. Soc. Lond. 34, 240-346. Lapworth, C. and Wilson, J.1870. The Lower Silurian rocks in the neighbourhood of Galashiels. Trans. Edinb. Geol. Soc. 2, 46-48.
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