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Millennium Wall Sections

TYPE/AREA: Peak District: Random Limestone(1), Coursed Gritstone(2)
Derbyshire DSWA Branch Click on above image to enlarge		STONE/GEOLOGY Types/Ages - (1) Bee Low Limestone, Lower Carboniferous (330 million years) (recycled from Hartington) - deposited in tropical seas. (2) Gritstone Crawshaw Sandstone, Lowermost Coal Measures, Upper Carboniferous (315 million years recycled from Alton) - deposited by major rivers flowing in from the east.

This section contrasts the two main types of walling to be seen over large parts of northern Derbyshire - limestone to the west and gritstone to the east and north. The more irregular fracture of the limestone produces a random style, whereas gritstone, often thinly bedded and more easily shaped, lends itself to regular coursing. A step/squeeze stile here divides the two types. These two walls show all the key features of limestone (numerous fossils) and sandstone (grains). As in most rocks the colour is due to iron staining.	WALLERS - Gordon and Jason Wilton (Limestone), Tony Martin and Shaun Graney (Gritstone). SPONSORS - D G Brailsford, Honeycroft Farm, Alton, Chesterfield (Sandstone), and P J Mycock, Friden Grange Farm, Hartington (Limestone).

TYPE/AREA: Peak District: Random Limestone(1), Coursed Gritstone(2)

Derbyshire DSWA Branch

Click on above image to enlarge

STONE/GEOLOGY

Types/Ages -
(1) Bee Low Limestone, Lower Carboniferous (330 million years) (recycled from Hartington) - deposited in tropical seas.

(2) Gritstone Crawshaw Sandstone, Lowermost Coal Measures, Upper Carboniferous (315 million years recycled from Alton) - deposited by major rivers flowing in from the east.

This section contrasts the two main types of walling to be seen over large parts of northern Derbyshire - limestone to the west and gritstone to the east and north. The more irregular fracture of the limestone produces a random style, whereas gritstone, often thinly bedded and more easily shaped, lends itself to regular coursing. A step/squeeze stile here divides the two types. These two walls show all the key features of limestone (numerous fossils) and sandstone (grains). As in most rocks the colour is due to iron staining.

WALLERS - Gordon and Jason Wilton (Limestone), Tony Martin and Shaun Graney (Gritstone).

SPONSORS - D G Brailsford, Honeycroft Farm, Alton, Chesterfield (Sandstone), and P J Mycock, Friden Grange Farm, Hartington (Limestone).

TYPE/AREA: South Wales Pennant
South Wales DSWA Branch Click on above image to enlarge		STONE/GEOLOGY Type and Age - Blue Pennant Gritstone, Coal Measures, Carboniferous (310 million years). Gritstone - (i.e. a coarse sandstone). These medium to coarse grained sandstones resulted from large rivers eroding the Devonian rocks of South West England, spreading great deltas over the Coal Measures of South Wales, to Forest of Dean and Bristol areas. Grains of quartz, mica and feldspar can be seen - all are the weathering products of granite. Source - Gelligaer Quarry, Trelewis, Treharris, Merthyr Tydfil.

This stone can occur as massive beds but is often flaggy and makes an excellent hard walling stone. It splits along bedding planes (thin layers of mica flakes assist this process). They produce a neat though randomly coursed appearance. The inherent colour of the rock is grey but vertical joint faces are often coated naturally with a brown iron oxide stain ('rusty rocks') resulting from the weathering of iron pyrite, mainly derived from coal seams and mudstones. Similar walls are seen from Carmarthenshire eastwards to the Bristol area.	DYKERS - Ken Young and Mike Hall. SPONSOR - Pioneer Aggregates (UK) Ltd.

TYPE/AREA: South Wales Pennant

South Wales DSWA Branch

Click on above image to enlarge

STONE/GEOLOGY

Type and Age - Blue Pennant Gritstone, Coal Measures, Carboniferous (310 million years). Gritstone - (i.e. a coarse sandstone). These medium to coarse grained sandstones resulted from large rivers eroding the Devonian rocks of South West England, spreading great deltas over the Coal Measures of South Wales, to Forest of Dean and Bristol areas. Grains of quartz, mica and feldspar can be seen - all are the weathering products of granite.

Source - Gelligaer Quarry, Trelewis, Treharris, Merthyr Tydfil.

This stone can occur as massive beds but is often flaggy and makes an excellent hard walling stone. It splits along bedding planes (thin layers of mica flakes assist this process). They produce a neat though randomly coursed appearance. The inherent colour of the rock is grey but vertical joint faces are often coated naturally with a brown iron oxide stain ('rusty rocks') resulting from the weathering of iron pyrite, mainly derived from coal seams and mudstones. Similar walls are seen from Carmarthenshire eastwards to the Bristol area.

DYKERS - Ken Young and Mike Hall.

SPONSOR - Pioneer Aggregates (UK) Ltd.

TYPE/AREA: Caithness, Highland Region, Scotland
Caithness DSWA Branch Click on above image to enlarge		STONE/GEOLOGY Type and Age - Caithness Flagstone, Middle Devonian (Eifelian) (380 million years). These siltstones and fine grained laminated sandstones were formed in vast lake, extending from Caithness through Orkney and Shetland. They are often called slates on account of the laminated nature, but they are not slates in geological terms (i.e. they are not metamorphic rocks). Source - Spittal Mains Quarry, Caithness.

The thin laminated nature and small size of this stone means that this dyke took far longer than all other dykes to complete. There is a general gradation from large at the base to small at the top. This style is seen in much of Caithness and Orkney. Slabs of the stone were used intricately in several brochs here and in ancient settlements on Orkney such as Scara Brae. Larger slabs were also used in this area to make 'flag fences' in the same way as the Cumbrian and Welsh slates. Some of the stone surfaces show signs of tracks, burrows and polygonal sun cracks as shallow lake muds which formed this stone dried out.	DYKERS - George Gunn and Sue Rainbow. SPONSOR - J W Sutherland, Caithness Stone Industries Ltd.

TYPE/AREA: Caithness, Highland Region, Scotland

Caithness DSWA Branch

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STONE/GEOLOGY

Type and Age - Caithness Flagstone, Middle Devonian (Eifelian) (380 million years).

These siltstones and fine grained laminated sandstones were formed in vast lake, extending from Caithness through Orkney and Shetland. They are often called slates on account of the laminated nature, but they are not slates in geological terms (i.e. they are not metamorphic rocks).

Source - Spittal Mains Quarry, Caithness.

The thin laminated nature and small size of this stone means that this dyke took far longer than all other dykes to complete. There is a general gradation from large at the base to small at the top. This style is seen in much of Caithness and Orkney. Slabs of the stone were used intricately in several brochs here and in ancient settlements on Orkney such as Scara Brae. Larger slabs were also used in this area to make 'flag fences' in the same way as the Cumbrian and Welsh slates. Some of the stone surfaces show signs of tracks, burrows and polygonal sun cracks as shallow lake muds which formed this stone dried out.

DYKERS - George Gunn and Sue Rainbow.

SPONSOR - J W Sutherland, Caithness Stone Industries Ltd.

TYPE/AREA: Random Double Dyke
West of Scotland DSWA Branch Click on above image to enlarge		STONE/GEOLOGY Type and Age - Quartz Dolerite. This igneous rock was intruded below ground into sedimentary rocks. As the rock cooled slowly it is more coarsely crystalline than basalt (formed by lavas at the surface). The presence of quartz means that it is also slightly more acidic than basalt. It is too alkaline (and dark) to be a granite. Source - Duntillan Quarry, Whitburn, West Lothian.

The stone locally known as Black Whin (whin is a hard, often dark stone in Southern Scotland and Northern England). This pattern is built to a specification of 1865. The throughstones, known as the 'thruband', project on either side. The dyke is topped by a 'rough cope' of large irregular stones. The angularity and hardness (which discourages trimming) of the stone defines the overall style.	DYKERS - Hugh and Rosie Allan, John Harper, Irwin Campbell, Paul Millard. SPONSOR - Tradstocks Ltd, Thornhill, Stirling.

TYPE/AREA: Random Double Dyke

West of Scotland DSWA Branch

Click on above image to enlarge

STONE/GEOLOGY

Type and Age - Quartz Dolerite.

This igneous rock was intruded below ground into sedimentary rocks. As the rock cooled slowly it is more coarsely crystalline than basalt (formed by lavas at the surface). The presence of quartz means that it is also slightly more acidic than basalt. It is too alkaline (and dark) to be a granite.

Source - Duntillan Quarry, Whitburn, West Lothian.

The stone locally known as Black Whin (whin is a hard, often dark stone in Southern Scotland and Northern England). This pattern is built to a specification of 1865. The throughstones, known as the 'thruband', project on either side. The dyke is topped by a 'rough cope' of large irregular stones. The angularity and hardness (which discourages trimming) of the stone defines the overall style.

DYKERS - Hugh and Rosie Allan, John Harper, Irwin Campbell, Paul Millard.

SPONSOR - Tradstocks Ltd, Thornhill, Stirling.

The text describing each section of wall is also set out on information panels at each point of the Millennium Wall at the National Stone Centre.

West Yorkshire, Cotswolds, South Yorkshire, South East Scotland
S.W. Scotland, Central Scotland, Isle of Sky, Cumbria
Northumbria, Cheshire, Lancashire, Sutherland
Cumbria (Slate), North Wales