CALCH Day 3 Part 1 – Fine Liming

Today, Sarah and I went to Llandovery to deliver an educational workshop to a local home education group. The group consists of children and young people of all ages all of whom were very eager to hear about the CALCH project in advance of a field-trip to the site sometime next week (weather permitting).

In this post I will outline some of the information that we passed on today along with a quiz that we’re happy for you to use on education visits to the CALCH.

The kilns and lime production

We don’t know exactly how many kiln remains there are on the Black  Mountain – there must be hundreds. What we do know is that there are too many to count including many that are buried under spoil from later kilns. The mountain is covered in kilns from many generations of lime processing, from the earliest ‘clamp’ kilns, to ‘flare’ kilns to the latest ‘draw’ kilns. Clamp kilns were constructed using peat and earth – these are easy to identify as they leave horse shoe shaped lumps in the ground. Flare kilns produce more lime at the end of the process and lime is removed by breaking an arch built into the kiln structure.

Flare kiln illustration courtesy of DAT

Flare kiln illustration courtesy of DAT

The most modern kiln type present on the Black Mountain is Draw kilns. In these kilns, the coal and limestone are arranged in such a way that the burning process can be constant. These later kilns allowed produced lime in such a large scale that they underpinned the boom of a large quicklime industry Carmarthenshire. Many of the later kilns at Herbert’s Quarry (affectionately named after David John Herbert, one of the last owners of the quarry) had names however we do not know which name goes with which kiln – the only kiln we can name for certain is Seren (the kiln next to David Davies’ monument).

Draw kiln illustration courtesy of DAT

Draw kiln illustration courtesy of DAT

Nowadays, these disused kilns are the perfect home for various bat species so it is important to be careful not to disturb them!


There are inherent dangers involved with the production of quicklime from the initial quarrying of limestone to the removal of carts full of the ‘white stuff’ to nearby farmland. Quarries, of course, are dangerous places; falling stones and explosives being the major contenders for damaging things (people included). The burning of the lime is, of course, hot, and the removal of the burnt lime is dangerous as the finished product is caustic (this means that it burns through organic material) and can seriously damage a person if it lands on their skin. Even the removal of quicklime in horse drawn carts could be hazardous – these is a monument to one David Davies, a 22 year old man who tragically died as he was crushed by his lime laden cart after his horse bolted.

David Davies monument photo courtesy of DAT

David Davies monument photo courtesy of DAT

The Rebecca Riots

This important part of Welsh history came about due to the extreme tolling of the roads leading out from the Black Mountain. So many tolls had been set up – at one point there was a toll point every 3 miles! – that it had become more costly to remove the lime from the mountain than the lime was worth on the market! Sick of the high cost of tolls the local people revolted in what is now known as the Rebecca Riots.

Life on the Back Mountain

Lime production was seasonal work; during the lime production process the kiln workers would live on the Black Mountain in little stone cottages next to the lime kilns. They would venture onto the mountain at the start of the week and take enough food too last them the week. A journal by Mr Tom Williams of Myddfai documents that they would take ham, bread and vegetables as their provisions for the week (read more of this document on the CALCH website).

Geology and biology

Other interesting occurrences on site include unusual tufa formations and rare alkaline loving plants; Butterwort and Mossy Saxifrage.

Tufa is a calcium rich deposit formed when water washes thorough heaps of waste lime (spoil heaps). The water dissolves calcium minerals from the spoil and later deposits them as strange looking tufa formations. The amazing thing about tufa formation on the Black Mountain is that it usually only forms within cave systems!

Tufa, courtesy of DAT

Tufa, courtesy of DAT

The star-shaped Butterwort and Mossy Saxifrage are plants which thrive in alkaline conditions. Fortunately for these plants lime is an alkaline substance which makes the area around Herbert’s Quarry a perfect habitat in which they can thrive.

Butterwort, photo courtesy of DAT

Butterwort, photo courtesy of DAT

Saxifrage, photo courtesy of DAT

Saxifrage, photo courtesy of DAT

You can find the quiz here


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