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Ruthin's Building Materials - Sources and History

Brian Hubble

Members' Talk, December 2018.  Summary.

Building materials from the ground are usually heavy, bulky and awkward to transport. They are generally of relatively low value, therefore transport costs account for a high proportion of the cost of the materials. This was especially true when the main method of transport was by packhorse or cart on poor, unmade roads.

This means that most communities had to use whatever materials were available locally. Given the varied geology across Britain, this meant that building materials, and therefore architecture, varied greatly, leading to many styles of vernacular architecture.


Ruthin's local resources.

1. Silurian Schists form the higher ground which flanks Dyffryn Clwyd to east and west.

2. Carboniferous Limestone lies at depth in the downfaulted trough which forms the Vale. This outcrops on the flanks, particulatly to the west.

3. Permo-triassic sandstone overlays the limestone, forming much of the valley floor.

4. Drift (recent glacial and river deposits) form a thin, varied and discontinuous veneer on the surface.


The very resistant schists are difficult to quarry and to dress - there are, therefore, not used as a building stone. The only significant quarry within the Vale is Craig Lelo, where Greywacke replaces the schists, providing very good road aggregate.

At the head of the Vale, on Bwlch Oernant (Horseshoe Pass) the schist gives way to slate. This slate is not the same as the Cambrian and Ordovician slates of North-West Wales. The Oernant quarry was producing roof slates in the 17thC. It's neighbours produced slab.

It is likely that the first slates in Ruthin were from these sources, probably carried by pack animals. The later Moelfferna quarry (roof slates) and its neighbours Penarth and Deeside, above Glyndyrdwy, were also a likely source of slate for Ruthin.

A smaller slate operation to the north west, at Nantglyn, produced slab, and this was used for fireplaces in Ruthin Gaol in the 1770s..

Carboniferous Limestone

Formed in a tropical marine environment from the Calcium Carbonate secretions on untold billions on tiny foramanifera, as well as the hard remains of other marine creatures, this hard rock is naturally cemented. The strata are, however, crossed by horizontal bedding planes and vertical joints which favour quarrying into rough blocks. Several buildings in Ruthin display fossils in their walls.

Within the local area there are four principal divisions - the Llanarmon (oldest), Leete, Loggerheads and Cefn Mawr limestones.


These vary slightly in texture, colour and fossil content.


Brachiopod, St. Peter's Church                       Belemnites, Ruthin Gaol                               Tubular Corals, Town Hall

Changing use of Carboniferous Limestone over time - 600 years apart.

In the older buildings rough-and-ready walls were built with undressed blocks and a lot of mortar, as shown here (right) at The Old Stables.

By the 14thC larger and more regular - but rough-hewn blocks - were in  use, as in the Pendist - former Natwest bank. (below left). Later 19thC and early 20thC buildings used machine-cut ashlar blocks of regular size and shape - with a minimum of mortar, as it the Gaol, below right.


Three local quarries provided the stone - Craig y Ddiwart (Ruthin), Denbigh, and Eyarth. Eyarth stone was used in County Hall - probably the last significant local use of this stone. !1907). The different colorations of the four limestone formations were used well by the architect of the Town Hall.

Permo-Triassic Sandstone.

This rock, known as the Kinnerton Formation, outcrops along a number of local roadsides. Formed in hot, arid conditions from sand - dune deserts it does not contain cementing compounds. This makes it relatively easy to quarry and to carve into attractive shapes and designs. However this is also its weakness, as it is subject to weathering.


Sandstone exposure, Ffordd Llanrhydd.                        Sandstone embellishments              Ty Coch, the main sandstone-only 

Note the dune bedding.                                                                                                    building in Ruthin


Severe weathering, Roman Catholic Church


Sandstone quarrying in the town has left no trace. It is likely that some stone was taken immediately adjacent to the Castle.

At Hirwaen, 3 miles to the east, is this quarry face. This was the source of the sandstone use in Cornwallis Wests's 1850s mansion at Ruthin Castle - probably the last use of this stone.

Sandstone and Limestone in partnership.

The two stones complement each other in an attractive colour combination, and in the architecture - Limestone provides the strength of the walls, sandstone the shaped doorways, window surrounds, and decorations. For 600 years the two stones were used in this way. Is this Ruthin's vernacular architecture?


             Ruthin Castle curtain wall                                 Town Mill                                                Castle Gateway

                    St. Peter's Church                                            Almshouses                                            St. Mwrog's Church

Llanfwrog ch doored.jpg

Drift - Brick-making.

The Myddletons opened a brickyard to the north of Ruthin in the 17C, using the glacial boulder clay. 

This is marked by Brickfields Lane and Cae Bricks today. The bricks were an attractive red but of poor quality. At first the fuel must have been wood or charcoal. The bricks themselves were hand-made. A railway connection in 1862 led to a degree of mass-production, coal now being available for the kilns, and the bricks were more regularly shaped and the frog was branded 'RUTHIN'. However the inferior clay and competition from the better quality, cheaper, and more varied bricks from the North-East Wales coalfield led to the demise of the works in, probably, the 1880s.

Several brick buildings have been rendered.


Ruthin Brick in Clwyd Street

Post-railway resources

The new resources from further afield, available after the coming of the railway in 1862, led to the immediate demise of quarrying the attractive but friable local sandstone. A superior and stronger, if not so colourful, alternative was the Carboniferous Cefn y Fedw stone which forms Ruabon mountain. This became a favourite in Ruthin - still alongside the limestone, or with Ruabon brick - as the town expanded in the latter half of the 18C. A marine sandstone, it displays deltaic current bedding and benefits from cementing compounds.

Here are some examples.

80. brick ruthin ed.jpg

               Town Hall                                                 Bathafarn Chapel                                            Police Station


Another replacement for the Ruthin sandstone was Runcorn stone ( as used in Liverpool,Anglican Cathedral) - seen here (left) in County Hall, 1907 alongside the Eyarth Limestone.

Some buildings were using the Cefn y  Fedw sandstone before the coming of the railway - the 1770's Gaol (below left) and the facade of the  Record Office (right) used this stone at considerable expense.

The classic portico  of the Record Office (now the Library) is from 1855 -  also pre-railway. It would be interesting to know how these superb columns (one-piece, and in excellent condition) were transported over the Llandegla moors!

The Peers Memorial in St. Peter's Square is an attractive mix of Eyarth Limestone and sandstone from both Runcorn and Gwespyr, Flintshire.


Railways also encouraged the use of superior Caernarfonshire and Ffestiniog slate.


Modern Times

In the 20thC as marketing and transport networks expanded, local materials ceased to dominate - and in fact have virtually disappeared.

Exotic rocks can be seen - the Larvikite (from Norway) columns on County Hall, Carrara marble (or similar) for the old cinema steps, Yorkstone paving from Halifax on the town centre streets (and, from Idle, near Bradford, the County Hall steps), Aberdeen granite for the War Memorial, 'foreigners' of indeterminate origin - but not Welsh - in walls around the town - and the superb fossiliferous kerbstones on St Peter's Square, possibly from Halkyn Mountain, otherwise from Wirksworth, Derbyshire.

Recent buildings now use materials not directly related to geology. The new County Hall, Craft Centre, and Glasdir schools are all fine buildings, but could, in terms of materials, be anywhere in the western world.

The connection between a town and its local geology is definitely a thing of History.

Footnote - from the opening of the English Presbyterian Church 1893


The building is distinctly an ornament to Ruthin, being carried out in pure Gothic style, and it stands in a charming situation, quite close to the centre of the town and the station, and at the same time affording from its grounds a magnificent prospect of the Vale and its confining mountains.  The structure is of Eyarth Limestone, a hard, pink variety, which is very effective when used in this case.  The main portion of the outside walls is undressed, each stone being tooled only on the edge, while the quoins of the corners and buttresses are dressed and the architectural result is excellent……………..

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