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Survey Details for BLNGWGL019 - 2026-06-09

BLNGWGL019

Geological Landscape

Blaina

Blaenau Gwent

2002-09-01

  • Level 1: Mountain and upland valley
  • Level 2: Glaciated mountain terrain
  • Level 3: Glacial mountain valley

Monitoring

Q1 - Date of monitoring?

  • 2013-03-01

Q1a - Monitoring undertaken by

  • Includes Regionally Important Geological Sites selected through the South Wales RIGS survey (2013). Includes key geomorphological features as landscape components.

Q1b - Has this record been updated following monitoring work?

  • This record has been updated following monitoring work as more up to date information is available

Q1c - Change indicated by

  • Policies, plans & information resources
    • South Wales RIGS survey (2013).

Q1d - What has changed?

  • Description
  • Evaluation
  • Condition & Trend
  • Recommendations

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

  • Yes
    • Site visits for original survey.

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

  • No

Description

Q3 - If Classification is "Other", specify here

  • Empty value

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

  • E upland plateau and less steep slopes of asymmetrical U-shaped, NW-SE Ebbw Fach valley, in S- to SW-dipping Pennant sandstones (Upper Carboniferous), cut by N-S steep sided Cwm Celyn tributary valley. Resistant Hughes Beds sandstones form the higher rounded plateau of Mynydd James, with Rhondda-Brithdir sandstones in valley slopes, forming the W slopes of Cwm Celyn and Mulfran. Extensive areas of landslips affecting the Rhondda and Brithdir Beds, onto lower, oversteepened, mudstone slopes, e.g. E Pentwyn, Bourneville,.which have W-facing scarps. Coal adits, tips and shafts along valley slopes. Head flanking lower, W-facing valley slopes, and some boulder clay. NW-SE faults across Pennant plateau.

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

  • Sedimentary

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

  • Carboniferous

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

  • Sandstone

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?

  • Glacial mountain valley

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

  • Stratigraphic formation(s)
    • Rhondda-Hughes Beds - South Wales Pennant Fm (Upper Carboniferous)
  • Superficial deposits
    • Head, boulder clay
  • Structural features
    • NW-SE faults
  • Active processes
    • Fluvial
  • Past processes
    • Glacial, periglacial

Q7 - What additional subsidiary Level 3 components are notable?

  • Upland valley slope
  • Upland plateau
  • Mass movement
  • Mineral workings

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

  • Glacial U-shaped valley
  • Landslip (active)
  • Landslip (ancient)
  • Coal / mineral spoil tips
  • Slope
  • Hill top

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

  • Fluvial
  • Empty value

Q10 - Are there components of significant hydrological importance?

  • Yes
    • Ebbw Fach valley.

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

  • Yes
    • High permeability soils.

Q12 - Is there current mineral extraction?

  • No

Q13 - Has there been mineral extraction in the past?

  • Yes
    • Coal

Q14 - Are there SSSI/GCR sites here?

  • No

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

  • Yes
    • Bournville Landslide (RIGSID 785, part): Landslide.

Condition

Q16 - Value

  • High
    • Shows aspects of Pennant sandstones stratigraphy, with significant large landslips (e.g. E Pentwyn, Bournville; Siddle et al. 2000).Includes major part of Bournville Landslide RIGS (RIGSID 785, part; Landslide).

Q17 - Condition

  • Fair
    • Upland plateau and valley sides with landslips developing as a consequence of coal mining.

Q18 - Trend

  • Declining
    • Upland plateau and valley sides with landslips developing as a consequence of coal mining.

Recommendations

Q19 - Existing management

  • Generally Appropriate

Q20 - Existing management remarks:

  • Neutral - Upland plateau and valley sides with landslips developing as a consequence of coal mining.

Q21 - Principal management recommendations

  • Upland plateau and valley sides with landslips developing as a consequence of coal mining - monitor and assess if risks outweigh geotechical interest before considering stabilisation. Maintain natural systems and ensure that RIGS are safeguarded using Local Plan policies and constraint mapping and that other features of particular geological or geomorphological significance in the area are not lost/damaged due to development, etc.

Q22 - Guideline

  • Long Term
    • Upland plateau and valley sides with landslips developing as a consequence of coal mining - monitor and assess if risks outweigh geotechical interest before considering stabilisation.
  • Long Term
    • Maintain natural systems and ensure that RIGS are safeguarded using Local Plan policies and constraint mapping and that other features of particular geological or geomorphological significance in the area are not lost/damaged due to development, etc.

Tolerance To Change

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

  • Yes
    • Monitor large landslip sites and assess if risks outweigh geotechical interest before considering stabilisation. Maintain natural systems and ensure that RIGS are safeguarded using Local Plan policies and constraint mapping and that other features of particular geological or geomorphological significance in the area are not lost/damaged due to development, etc.

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?

  • None
    • Aspect Area boundaries plotted at 1:25,000.

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

  • Other
    • 1:50 000 BGS Geological map sheet; 1:25 000 OS Explorer map sheet; Digital Terrain Model compiled from OS panorama digital terrain data (50m resolution)

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

  • 1:25,000

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

  • AA corresponds to outcrop of Pennant sandstones on E side of Ebbw Fach glacial valley.

Evaluation

Q29 - Evaluation Criteria: Research Value

  • High
    • Shows aspects of Pennant sandstones stratigraphy, with significant large landslips (e.g. E Pentwyn, Bournville; Siddle et al. 2000). Includes major part of Bournville Landslide RIGS (RIGSID 785, part; Landslide).

Q29a - Evaluation Criteria: Educational Value

  • High
    • Shows aspects of Pennant sandstones stratigraphy, with significant large landslips (e.g. E Pentwyn, Bournville; Siddle et al. 2000). Includes major part of Bournville Landslide RIGS (RIGSID 785, part; Landslide).

Q30 - Evaluation Criteria: Historical Value

  • Moderate
    • Shows aspects of Pennant sandstones stratigraphy, with significant large landslips (e.g. E Pentwyn, Bournville; Siddle et al. 2000).

Q31 - Evaluation Criteria: Rarity / Uniqueness

  • Moderate
    • Shows aspects of Pennant sandstones stratigraphy, with significant large landslips (e.g. E Pentwyn, Bournville; Siddle et al. 2000).

Q32 - Evaluation Criteria: Classic Example

  • High
    • Shows aspects of Pennant sandstones stratigraphy, with significant large landslips (e.g. E Pentwyn, Bournville; Siddle et al. 2000).

Q33 - Evaluation Criteria: Overall Evaluation

  • High
    • Shows aspects of Pennant sandstones stratigraphy, with significant large landslips (e.g. E Pentwyn, Bournville; Siddle et al. 2000). Includes major part of Bournville Landslide RIGS (RIGSID 785, part; Landslide).

Q34 - Justification of overall evaluation

  • Shows aspects of Pennant sandstones stratigraphy, with significant large landslips (e.g. E Pentwyn, Bournville; Siddle et al. 2000). Includes major part of Bournville Landslide RIGS (RIGSID 785, part; Landslide).

Bibliography

Q35 - Sources and additional assessments

  • 1:50 000 BGS Geological Map sheet 232 Abergavenny, S&D, 1990; 1:25 000 Explorer Map OL12 Brecon Beacons National Park, Western and Central Regions ; Digital Terrain Model compiled from OS panorama digital terrain data (50m resolution); 1:100 000 Groundwater Vulnerability Map, Environment Agency. Sheet 36, Gwent, South and Mid Glamorgan, 1996; 1:625 000 Geological Map of the UK: Quaternary Geology, S sheet, 1977; Barclay, W.J., 1989. Geology of the South Wales Coalfield, Part II, the country around Abergavenny. Memoir of British Geological Survey, Sheet 232, HMSO, 3rd edition, 147pp; Conway, B.W., Forster, A., Northmore, K.J. and Barclay, W.J., 1980. South Wales Coalfield Landslip Survey. Report of Engineering Dept of Institute of Geological Sciences, No. EG80/4; Conway, B.W. 1985 South Wales coalfield landslip survey. British Geological Survey. Siddle, H.J., Bromhead, E.N. and Bassett, M.G., eds, 2000. Landslides and landslide management in South Wales. National Museums and Galleries

Assessment

Q36 - Additional Assessments

  • South Wales RIGS survey (2013); LANDMAP monitoring project (2012-2013).

Q37 - Additional Comments

  • Additional Level 4 features include: Stream; Natural crags and inland outcrops.