Millennium Wall Sections

South West Scotland DSWA Branch

Click on above image to enlarge

STONE/GEOLOGY

Type/Age - Glacial erratic granite boulders. Pleistocene age (granites originally Lower Devonian). The boulders were rounded by weathering, particularly the grinding action of glaciers -  this contrasts with the more angular quarried rock of some other walls. The large white quartz and feldspar crystals and small specks of mica define the rock as granite.

Source - Pibble Forest. Gathered in process of field clearing.

Normally large stones are placed at the base and smaller in the upper levels. Where there is a range of sizes, smaller boulders are doubled up at the base with larger single ones placed, dyke-wide at the top. Some dykes are up to 2m high. The top section is often of very open construction -  daylight can be seen through it. It is suggested that this deters animals from jumping the dyke. To place the larger stones, it was necessary to roll them into position using a wooden plank as a ramp.

DYKERS - Garth Heinrich and Roger Lewis, assisted by Paul Craven

SPONSOR - John Miller, Pibble Forest, Gatehouse of Fleet.

Central Scotland DSWA Branch

Click on above image to enlarge

STONE/GEOLOGY

Type and Age - Sandstone Lower Devonian (400 million years).

This sandstone was formed by the erosion of mountains to the north and south by seasonal rivers in a semi-arid climate

Source - Strathmore Estates, Glamis, Angus.

DYKERS - Syd Mitchell, John Fenwick, Joyce Anderson, Dorothy Spencer, John Cameron, Kate Armstrong, May Hirst, Margaret Williamson.

SPONSORS - Strathmore Estates, Glamis Castle; Marley Building Materials, Glasgow; Keyline Builders Merchants, Dundee.

Isle of Sky DSWA Branch

Click on above image to enlarge

STONE/GEOLOGY

Type and Age - Basalt - Tertiary Lava (63 million years). Basalt is a fine grained basic igneous rock, formed as volcanic lavas cooled. The lava fields ranged from the Inner Hebrides across Iceland to Greenland. Volcanoes are still active in Iceland. They began forming just as the dinosaurs were dying out. Basalt is black when freshly broken, but weathers a dull grey.

Source - Recycled field wall.

This is the standard style of dyke built throughout Skye, although the type of stone used may vary. Massive boulders used at the base may make up as much as 75% of the dyke height. The cope may be of rubble (rather than single stones) or as here, of turf. Where stone copes are used, they overhang to deter sheep from jumping over the dyke. The style has been in use for at least 200 years.

WALLERS - Hector Nicolson, Neil Tonagh, Louise Kerr, Martin Wildgoose.

SPONSORS - Curry Fund of the Geologist's Association; Skye Transport; Skye and Lochalsh Enterprise; John Muir Trust.

Cumbria (with assistance from Eden Valley) DSWA Branch

Click on above image to enlarge

STONE/GEOLOGY

Type and Age - Cumbrian green slate, Borrowdale Volcanic Series, Ordovician (470 million years). The Lake District green slates were formed when the ashes and tuffs ejected by large volcanoes, were metamorphosed by heat and pressure. They produced a rock which could be split along rough cleavage planes (most slates are metamorphosed mudstones and shales).

Source - Elterwater Quarry, Langdale Valley, Cumbria.

This style is widespread in Central and Southern Cumbria. It is typified by a broad base with many courses and through stones. The lowerstones are much larger than those higher up. The slabby cope stones, known as 'cams', slope downhill - this prevents them from slipping. The green colour is typical of this part of Cumbria, and is the result of complicated alumino-silicate minerals, produced in metamorphism - the crimson coloured staining is produced by hematite (iron oxide) being deposited on joint faces. The slight overhang of the cams deters sheep from jumping the wall.

WALLERS - John Stoddart, Andrew Loudon, Steven Allen, Brian Jones, Mike Houston.

SPONSORS - Burlington Slate Ltd (Slate), and Kirkstone Quarries Ltd (Transport).