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Survey Details for CRMRTGL013 - 2026-06-07

CRMRTGL013

Geological Landscape

Llangynog

Carmarthenshire

2008-12-30

  • Level 1: Lowland hills and valleys
  • Level 2: Undulating lowland hill terrain
  • Level 3: Undulating lowland hill terrain

Monitoring

Q1 - Date of monitoring?

  • No Answer

Q1a - Monitoring undertaken by

  • No Answer

Q1b - Has this record been updated following monitoring work?

  • No Answer

Q1c - Change indicated by

  • No Answer

Q1d - What has changed?

  • No Answer

Q1e - Has the information ever been verified in the field?

  • No

Q2 - Does this area have a special or functional link with an adjacent area?

  • Yes
    • Forms part of the Llangynog Precambrian to lowest Ordovician (Tremadoc) inlier (CRMRTGL013 and CRMRTGL088).

Description

Q3 - If Classification is "Other", specify here

  • Empty value

Q4 - What is the geographical and topographical character of this area?

  • Section of lowland plateau -which includes the Pen plas - Pel-lan area - with an undulating surface and depressions with glacial clay infil clay (Quaternary: Pleistocene), also peat in some. Dominated by Ordovician mudrocks. But includes the unique Llangynog Precambrian-Cambrian-Tremadoc (basal Ordovician) inlier. Geology varied including volcanic rocks, sandstones and mudrocks.

Q4a - Where bedrock dominated, what is the dominant bedrock type?

  • Sedimentary

Q4b - Where bedrock dominated, what is the age that characterises the aspect area?

  • Precambrian
  • Cambrian
  • Ordovician

Q4c - Where bedrock dominated, what is the major rock lithogy (-ies)?

  • Sandstone
  • Mudstone

Q4d - Where drift dominated, what is the dominant drift deposit?

  • No Answer

Q4e - Where drift dominated, what is the major sediment that characterises the area?

  • No Answer

Q5 - What is the characteristic Level 3 component of the area?

  • Undulating lowland hill terrain

Q6 - Which of the following is a significant contributor to the geological character of the area?

  • Stratigraphic formation(s)
    • Coomb Volcanic Formation, including Castell Cogan Rhylite Member, Coed Cochion Volcaniclastic Member [PRECAMBRIAN (Wrekin Terrane): NEOPROTEROZOIC III, including EDIACARAN PERIOD]; Allt y Shed Sandstone Formation [LOWER CAMBRIAN, ?COMLEY]; Treffgarne Bridge Beds Formation, Ogof Velvet Formation, Dolgellau Formation [UPPER CAMBRIAN, MERIONETH] and Sheinton Shale Formation [ORDOVICIAN, TREMADOC, including CRESSAGIAN]. Higher levels not mapped reliably, probably includes Ogof Hen Formation, Carmarthen Formation, Afon Ffinnant Formation, Colomendy Formation, Cwmfelin Boeth Formation, Ponyfenni Formation and Llanfallteg Formation [ORDOVICIAN, mainly ARENIG]; 'Didymograptus Shales' ('Bifidus Beds') recorded in N [ORDOVICIAN, LLANVIRN: ABEREIDIAN].
  • Superficial deposits
    • Glacial clay widespread (QUATERNARY: PLEISTOCENE (DEVENSIAN)).
  • Active processes
    • Stream, spring
  • Past processes
    • glacial

Q7 - What additional subsidiary Level 3 components are notable?

  • No Answer

Q8 - What Level 4 components are notable in this area?

  • Slope
  • Hill top
  • Spring
  • Urban / industrial development

Q9 - What active geological and geomorphological processes are significant in this area?

  • Stream, spring
  • Empty value

Q10 - Are there components of significant hydrological importance?

  • Yes
    • Stream, spring

Q11 - Are there any pedological processes that are significant in the area or have had a landscape forming effect?

  • No

Q12 - Is there current mineral extraction?

  • No

Q13 - Has there been mineral extraction in the past?

  • Yes
    • Volcanic rocks, etc

Q14 - Are there SSSI/GCR sites here?

  • Yes
    • Coed Cochion Quarry SSSI (SN333147) [Coed Cochion Quarry proposed GCR site: Precambrian Palaeontology. Coed Cochion GCR site: Precambrian of England and Wales].

Q15 - Are there geological SINC, 2nd tier, or RIGS sites in the area?

  • Yes
    • Dan-Lan-Y-Castell Quarry SSSI [Dan-Lan-Y-Castell Quarry GCR site (SN364165): Ordovician, Arenig-Llanvirn]; Cwm Crymlyn Road Section SSSI [Cwm Crymlyn GCR site (SN348174): Ordovician, Tremadoc]

Condition

Q16 - Value

  • Outstanding
    • Includes GCR / SSSI features of national / international importance. Includes RIGS features of at least regional importance.

Q17 - Condition

  • Good
    • Rural area with no significant development.

Q18 - Trend

  • Constant
    • Rural area with no significant development.

Recommendations

Q19 - Existing management

  • Generally Appropriate

Q20 - Existing management remarks:

  • Rural area with no significant development.

Q21 - Principal management recommendations

  • Ensure that no features or natural systems of geological or geomorphological significance in the area are lost or damaged (e.g. due to development or forestry). Ensure that SSSI features are maintained in favourable condition by implementation of management plans and ensure that RIGS are safeguarded using Local Plan policies and constraint mapping.

Q22 - Guideline

  • Long Term
    • Ensure that no features or natural systems of geological or geomorphological significance in the area are lost or damaged (e.g. due to development or forestry).
  • Long Term
    • Ensure that SSSI features are maintained in favourable condition by implementation of management plans and ensure that RIGS are safeguarded using Local Plan policies and constraint mapping.

Tolerance To Change

Q23 - Are there any significant threats to the current integrity and condition of the Earth Heritage features of the area?

  • Not known

Aspect Area Boundary

Q24 - To what level was this information site-surveyed?

  • Level 3

Q25 - At 1:10,000, how much of the Aspect Area boundary is precise?

  • Most
    • Aspect Area boundaries surveyed at 1:10,000 using aerial photographs, mapped at 1:25,000.

Q26 - What baseline information source was used for Aspect Area boundary mapping?

  • Other
    • 1:50,000 British Geological Survey maps, 1:10,000 aerial photographs (as stereo pairs), OS 1:25,000 Landranger topographical maps.

Q27 - If OS Data was used, what was the scale?

  • 1:25,000

Q28 - What is the justification for the Aspect Area boundaries?

  • Margins of low massif.

Evaluation

Q29 - Evaluation Criteria: Research Value

  • Outstanding
    • Includes GCR / SSSI features of national / international importance. Includes RIGS features of at least regional importance.

Q29a - Evaluation Criteria: Educational Value

  • High
    • Includes GCR / SSSI features of national / international importance. Includes RIGS features of at least regional importance.

Q30 - Evaluation Criteria: Historical Value

  • Outstanding
    • Includes GCR / SSSI features of national / international importance. Includes RIGS features of at least regional importance.

Q31 - Evaluation Criteria: Rarity / Uniqueness

  • Outstanding
    • Includes GCR / SSSI features of national / international importance. Includes RIGS features of at least regional importance.

Q32 - Evaluation Criteria: Classic Example

  • Outstanding
    • Includes GCR / SSSI features of national / international importance. Includes RIGS features of at least regional importance.

Q33 - Evaluation Criteria: Overall Evaluation

  • Outstanding
    • Includes GCR / SSSI features of national / international importance. Includes RIGS features of at least regional importance.

Q34 - Justification of overall evaluation

  • Includes GCR / SSSI features of national / international importance. Includes RIGS features of at least regional importance.

Bibliography

Q35 - Sources and additional assessments

  • CARNEY, J.N. et al. Geological Conservation Review Series 20; COPE, J.C.W. and RUSHTON, A.W.A. 1992, Geological Magazine 129, 543-552; ORDNANCE SURVEY 2005a., Explorer Map 177 (1:25, 000); INSTITUTE OF GEOLOGICAL SCIENCES 1967, Sheet 229, 1:50,000 Geological Series; STRAHAN, A. et al. 1909, Memoirs of the Geological Survey (England and Wales), HMSO.

Assessment

Q36 - Additional Assessments

  • None

Q37 - Additional Comments

  • Additional Level 4 features include: Stream; Disused quarry; Marsh/bog/fen.