Archive for category: Geoconservation

Local Geodiversity Sites are places where the variety of geology of the local area can be enjoyed and appreciated. In the Scottish Borders Council area, 35 potential LGS have been submitted to the Council for inclusion in the Local Development Plan (LDP) 2020.

The rolling hills of the Scottish Borders region stretch from the Berwickshire coast westwards to Dumfries and Galloway, in the north to the Pentland Hills and Edinburgh, with the southern boundary following the border with England. Most of the region is drained in an easterly direction by the 150 km River Tweed and its tributaries.

The solid geology is dominated by Lower Palaeozoic greywackes which form the upland areas to the north and west, such as the Lammermuir Hills, Moorfoot Hills and Ettrick Forest. Eastwards, in the lower Tweed valley, Devonian and Carboniferous sandstones and mudstones are interrupted by volcanic lavas, plugs and intrusions, such as the Eildon Hills, near Melrose. Upland landscapes are influenced by glacial erosion whereas the valleys contain thick sequences of glacial and alluvial deposits.

Read more about the survey work by Alison and Barry Tymon to identify Local Geodiversity Sites in the Scottish Borders Council area.

Highlights include the following accessible sites:

Cocklie Rig Head Quarry, looking east.

Cocklie Rig Head Quarry, Glencotho [NT 0898 2937]

Rarely exposed Wrae Limestone (Ordovician) is found in a small quarry to the east of the farmhouse at Glencotho. A quarry track to the south-east leaves the lane just beyond the farmhouse and leads past old lime kilns at NT 08717 29710 uphill about 700 m directly to the quarry.

General view of Cramalt Cutting from the lay-by.

Cramalt Road Cutting [NT 1985 2292 – NT 2013 2296]

A 200 m long road section can be found on the minor road overlooking Megget Reservoir, where there is a large lay-by. The face exposes the Queensberry Formation (Silurian Gala Group). At the east end are steeply dipping siltstones with a minor fault and on the bend in the road massive greywackes with flute marks, lineations and other minor sole structures are found. Tightly folded vertical laminated siltstones can be seen at the west end of the section. This is an excellent site for the study of greywackes and their structures.

Downstream view of Edrington Cliff from the footbridge over Whiteadder Water to show the overgrown river side quarry and the exposed rock on the river’s edge.

Edrington Cliff [NT 9400 5335]

The site is a river cliff on the east bank of Whiteadder Water near to Edrington Castle exposing Ballagan Formation (Lower Carboniferous) sandstones. The medium-bedded pink sandstones dip gently downstream towards the south and some beds have marked cross-bedding. The cliff is visible across the Whiteadder Water from a footpath accessed from the lane to Edrington Castle Farm. Cross the river on the footbridge and walk south along the river bank.

Mid Hill (right peak) and Wester Hill (left peak) from North Hill.

Eildon Hills North Hill [NT 5543 3283], Mid Hill [NT 5481 3223], Wester Hill [NT 5483 3160], Little Hill [NT 5455 3195]

These well-known hills above Melrose dominate views for many miles around. They are largely composed of trachytic sill-like intrusions (sometimes known as the Eildon Hills laccolith) lying above Silurian greywackes and horizontal Upper Old Red Sandstone. The igneous rocks have been recently dated at 352 million years old (Lower Carboniferous). There are many well-signposted public footpaths across the hills. St Cuthbert’s Way long distance footpath runs through the col between North Hill and Mid Hill.

Waterfall of horizontal crinoidal Carboniferous Blackhall Limestone, underlain by mudstones. The plunge pool (Peggy’s Pool) is formed by the undercutting of the less resistant mudstones.

Habbie’s Howe [NT1694 5648 – NT 1783 5657]

The River North Esk flows through a steep-sided valley between Amazondean and Craigy Bield in the grounds of Newhall, near Carlops. The rocks consist of limestones, sandstones and mudstones of the Carboniferous Lower Limestone Formation and are exposed in the sides of the valley, in a small waterfall and in an old quarry at Mill Bridge. The valley, with its caves which have been modified by eighteenth century landscaping, was probably formed by the erosion and undercutting of less resistant sandstones by glacial meltwater. The valley is linked to the pastoral comedy, ‘The Gentle Shepherd’ by Allan Ramsay 1725. There are many footpaths through the woods, which are accessible by road and tracks from the public car park in Carlops.

View of Hell’s Cleugh from above the confluence with Mill Burn, looking SW.

Hell’s Cleugh, Stobswood [NT 738 549 – NT 739 549]

Exposures of the Great Conglomerate (Lower Old Red Sandstone) in Hell’s Cleugh are found in a deep gorge. The badly-sorted conglomerate, composed largely of greywacke pebbles with a sandy matrix, is exposed on both sides along the gorge, in gullies, stacks and cliffs. There is a large car park at Hardens Hill [NT 741 541] and the easiest access across the boggy moorland is to take the field track from the car park to the mast by the plantation, then walk due north skirting the plantation, keeping to the west of the minor gullies to avoid wet ground, and dropping down to the cleugh at its confluence with Mill Burn. Total walking distance is about 4 km.

Shingle beach showing exposures of grey bedded volcanic ash.

Preston Bridge, Duns [NT 7871 5678 (Preston Bridge) – NT 7835 5710 (Anger my Heart)]

The permissive footpath from the car park next to Preston Bridge upstream as far as Anger my Heart (rapids across Whiteadder Water) gives access to basalts found under the bridge, intruded into Upper Devonian gently dipping sandstones and cornstones with interesting sedimentary features. Upstream, a shingle beach has exposures of grey bedded ash. At Rocky Corner [NT 7831 5702] there is an unbedded exposure of ash and blocks of lava which juts out into the river and a few metres upstream columns of fresh basalt can be seen in the river.

View of Smailholm Tower looking from the sandstone beds at the millpond towards the basalt crags.

Smailholm Tower [NT 638 347]

Smailholm Tower stands on crags of dark grey basalt, thought to be lava flows, which are part of the Lower Carboniferous Kelso Volcanic Formation. Some of the crags have columnar jointing, but elsewhere jointing is irregular and generally massive. An exposure of Devonian/Carboniferous medium grained, dark grey sandstone can be seen at the east end of the mill pond. Smailholm Tower is open to the public during the summer months and there is a small car park.

Quarry of vent agglomerate on the east side of South Minto Hill.

South Minto Hill [NT 5520, NT 5521, NT 5620, 5621]

The Minto Hills are two oval volcanic necks made of volcanic vent agglomerates intruded into Upper Old Red Sandstone rocks, which cannot be seen but which form the gentle slopes at the foot of the hills. Several small quarries and exposures on South Minto Hill show the features of the volcanic agglomerates. A public footpath runs from a small lay-by on the minor road north of Minto across a field to the col between the two hills and continues to Minto Kames.

A large andesite crag on the east side of Staerough Hill, looking north east.

Staerough Hill, Yetholm [NT 8327 – NT 8327]

Staerough Hill is composed of pink andesite lavas of the Cheviot Volcanic Formation, (Early Devonian), which can be seen in several crags and a small quarry on the steep hill slopes. Several of the lava flows, including the huge crag overlooking Kirk Yetholm on the north of the hill, are glassy and are called pitchstones. Parking is available at NT 840 277 at Halter Burn and there is a footpath which leads on to Staerough Hill from the lane nearby. Many of the old buildings in Kirk Yetholm are built of pitchstone and the church was rebuilt with pitchstone in 1836-37.