Din Lligwy historical RIGS Site

NRW RIGS no. 124 [SH 49735 86158]

GeoMôn Global Geopark original webpage

RIGS Statement of Interest:

Din Lligwy historical RIGS Site illustrates the use of limestone pavement for building material in prehistoric and historic times. The limestone (mainly limestone pavement) has been used on three separate occasions in prehistoric and historic times. It comprises the Neolithic Lligwy Chambered Tomb2 (c. 5000 BP), the well-preserved Romano-British hut group of Din Lligwy¹ and the twelfth century Hen Capel Lligwy3 The tomb² is one of a number of similar late Neolithic monuments peculiar to north-east Anglesey, and is representative of a somewhat degenerate last phase of this tradition. It has been fully excavated and has yielded much evidence of Anglesey’s prehistoric culture in the form of human and animal bones, flint tools and fragments of pottery. The huge 25,400 kg (25.4 tonne) capstone overlies a fissure in the underlying limestone bedrock. It is a slab of Carboniferous limestone (5.5m x 4.8m x 1.1m) showing solutional features on its surface typical of limestone pavement development. It was possibly moved a short distance from its original location by glacial action. In contrast, Din Lligwy¹ has been dated to the fourth century AD. The stone remains of this hut group consist of Carboniferous limestone. Many of the blocks carry solutional features, also suggesting derivation from the local limestone pavement. Construction is in dry stone throughout, consisting of inner and outer facings with a rubble infill. Hut foundations of both rectilinear and round form are present, enclosed within a polygonal wall. The site has been excavated over several years from 1905, revealing extensive evidence of metal working in iron, with four smelting-hearths being identified. The site’s importance is inferred from the high-quality pottery and non-ferrous metalwork found (including a silver ingot and a twisted bronze bracelet). The twelfth century Hen Capel Lligwy³ was rebuilt in its present form in the fourteenth century. It stands unroofed some 2km ENE of St Michael’s Parish Church, Penrhoslligwy, and formerly served as a chapel of ease to Llanallgo. The south side of the chapel was added in the sixteenth century. Most of the stone is locally derived Carboniferous limestone, much of it obtained from adjacent areas of pavement. Occasional blocks of other lithologies have also been used, including water-rounded boulders of Precambrain schist and Carboniferous sandstone which may have come from local glacial, river or beach deposits. Constructed originally in dry stone, later fourteenth century shelly mortar and also newer sixteenth century mortar were used in the modifications and additions. The three separate elements that make up this RIGS illustrate the exploitation of limestone pavement as a building material during the Neolithic and Romano-British periods, and again during the twelfth century. The specific uses indicate the changing cultures and building requirements. In all three cases, the use of local limestone pavement, unacceptable for conservation reasons today, was part of Anglesey practice for sound practical and geological reasons.

Geological setting/context: There are three main categories of RIGS selected for their historical importance: 1. Historical constructions (arbitrarily up to 2,000 years old) and/or archaeological constructions (arbitrarily more than 2,000 years old) where rock has been used and where the relevance of geology can be demonstrated. This type of RIGS can include castles, churches, ruins, lanes, walls, cromlechs and standing stones. 2. Sites or features related to the development of geological thought and geology as a science, such as sites where certain concepts or theories were developed or types of feature first explained (e.g. Hutton’s Unconformity). 3. RIGS commemorating the work and contributions of important geologists. These usually take the form of a monument (such as a grave) or memorial.

Network context of this site: Din Lligwy¹, Lligwy Chambered Tomb² & Hen Capel Lligwy³ are archaeological/historical constructions, and belong to category 1 of Historical RIGS (see above). They demonstrate the use of local limestone, mainly pavement-derived material, during three widely separated periods, when the purpose of the structures and the construction requirements differed but the geological source material remained the same. The geological importance of this site lies in its demonstration of the continued exploitation of the limestone pavement and other local geological resources in this locality for over 5,000 years.

References:

BAYNES, E.N. (1909). The excavation of Lligwy Cromlech, in the County of Anglesey. Archaeologia Cambrensis,217–231.

BAYNES, E.N. (1912) The Megalithic Remains of Anglesey (with illustrations). Transactions of the Honourable Society of Cymmrodorion, Session 1910–11, 3–91.

LYNCH, F.M. (1991). Prehistoric Anglesey. The archaeology of the Island to the Roman conquest (2nd ed.). The Anglesey Antiquarian Society, W.O. Jones, Llangefni, 88–90.

THE ROYAL COMMISSION ON ANCIENT & HISTORICAL MONUMENTS IN WALES & MONMOUTHSHIRE (1937 & 1960). An Inventory of the Ancient Monuments in Anglesey. HMSO, London, 133–137 & plates 12 & 13¹, & 132–133³.

WADE-EVANS, (1910). Parochialum Wallia. Transactions of the Honourable Society of Cymmrodorion, ****