Cloddiwyd calchfaen am ganrifoedd lawer ar hyd llain galchfaen Sir Gaerfyrddin gyfan, o’r Mynydd Du i’r arfordir yng Nghydweli, ac fe’i llosgwyd mewn odynau a adeiladwyd yn y chwareli i gynhyrchu calch i ffrwythloni’r tir. Y tollau a godwyd i gludo’r nwydd gwerthfawr hwn ar ffyrdd tyrpeg yn ystod y 1830au oedd un o’r prif faterion a sbardunodd Terfysgoedd Beca ym 1839 ac arweiniodd at chwalu llawer o dollbyrth a bariau offer ar rwydwaith ffyrdd tyrpeg.

Roedd calch yn ddeunydd pwysig yn y broses mwyndoddi haearn ac roedd calchfaen hefyd yn cloddio at y diben hwnnw. Roedd hyn yn wir hefyd am raean y maen melin a’r tywodfeini silica sy’n gorwedd rhwng y mesurau glo a’r gwelyau calchfaen yn y dilyniant daearegol, a gafodd eu cloddio a’u malu’n helaeth yn Sir Gaerfyrddin.

Gellir adnabod cannoedd o chwareli ac odynnau mawr a bach o hyd yn y dirwedd, er i losgi calch ddod i ben yn Sir Gaerfyrddin ar ddechrau’r 1970au ac erbyn hyn ychydig iawn o chwareli calchfaen sy’n gweithio yn y sir. O fewn cymuned Gorslas, ceir cyfres o chwarel galchfaen o’r ddeunawfed a’r bedwaredd ganrif ar bymtheg a chyfadeiladau llosgi calch – yn fwyaf nodedig chwareli Castell-y-garreg a Chapel Quarries i’r gogledd o Lyn Llech Owain ac ail Chwarel y Castell i’r gorllewin o Foelgastell.

Mae graeanu’r maen melin wedi cael eu cloddio ers canrifoedd fel y mae’r garreg garw, fel y mae’r enw’n awgrymu, yn ddeunydd ardderchog ar gyfer gwneud meini melin. Fodd bynnag, daeth yr oes ddiwydiannol â defnydd newydd ar gyfer yr adnodd hwn, gan fod cynnwys silica uchel y graig yn ei gwneud yn ddeunydd ardderchog ar gyfer leinin ffwrneisi haearn a dur. Cafodd y carreg gorlech ei wasgu i lawr i dywod silica ar gyfer y diwydiant mwyndoddi, a hefyd deunydd crai ar gyfer cynhyrchu briciau silica, a wnaed mewn niferoedd mawr yng Nghydweli. O fewn Gorslas ceir nifer o chwareli bychain ar hyd crib y garreg gorlech ond yr unig chwarel a chyfadeilad malu a gofnodwyd yw honno yng Nghwmper, i’r gorllewin o Foelgastell.

Limestone was quarried for many centuries along the whole of the Carmarthenshire limestone belt, from the Mynydd Du to the coast at Kidwelly, and was burned in kilns built at the quarries to produce lime to fertilise the land. The tolls charge to transport this valuable commodity on turnpike roads during the 1830s were one of the main issues that sparked the Rebecca Riots in 1839 and led to the smashing of many tollgates and toolbars on the turnpike road network.

Lime was an important material in the iron smelting process and limestone was also quarried for that purpose. This was true also of the millstone grit and silica sandstones that lie between the coal measures and the limestone beds in the geological sequence, which were extensively quarried and crushed in Carmarthenshire.

Many hundreds of large and small quarries and kilns can still be identified in the landscape, although lime burning came to an end in Carmarthenshire in the early 1970s and there are now very few working limestone quarries in the county. Within Gorslas community, there are a series of eighteenth and nineteenth century limestone quarry and lime burning complexes – most notably the Castell-y-garreg and Capel Quarries to the north of Llyn Llech Owain and a second Castle Quarry to the west of Foelgastell.

Millstone grits have been quarried for centuries as the rough stone, as its name implies, was an excellent material for making millstones. However, the industrial age brought a new use for this resource, as the high silica content of the rock made it an excellent material for lining iron and steel furnaces. The gritstone was crushed down into silica sand for the smelting industry, and also a raw material for the production of silica bricks, which were made in great numbers at Kidwelly. Within Gorslas there are numerous small quarries along the length of the gritstone ridge but the only recorded quarry and crushing complex is that at Cwmper, west of Foelgastell.