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Survey Details for MNMTHGL036 - 2026-06-04

MNMTHGL036

Geological Landscape

Penrhos

Monmouthshire

2006-11-24

  • 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?

  • No

Description

Q3 - If Classification is "Other", specify here

  • Empty value

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

  • Undulating terrain of low hills underlain by Lower Old Red Sandstone Group mudrocks (mainly Upper Silurian). Dissected by streams, bounded by the Trothy river system to the E and N and with a low escarpemnt to the NW and bounded by a low escarpment to the S formed by higher levels in the Lower Old Red Sandstone Group of Lower Devonain age. Probably includes areas of glacial/fluvioglacial deposist especially in the S along the A40 corridor and on the E side of the Nant y Wilcae valley as topography lower.

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

  • Sedimentary

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

  • Silurian

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

  • 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)
    • Lower Old Red Sandstone Group, Raglan Marls Formation (Silurian: Pridoli Series/Epoch-Lower Devonian, Lochovian Stage) with minor St. Maughan''s Formation (Lower Devonian: Lochkovian-Pragian stages), Senni Formation (Lower Devonian: Lochkovian-Pragian stages) in N only.
  • Superficial deposits
    • Minor glacial/fluvioglacial deposits include glacial/fluvioglacial sand and gravel and till (Quaternary: Pleistocene (Devensian)).
  • Active processes
    • Stream, spring.
  • Past processes
    • Glacial, fluvioglacial.

Q7 - What additional subsidiary Level 3 components are notable?

  • No Answer

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

  • Lake / reservoir (artificial)
  • 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?

  • Not known

Q12 - Is there current mineral extraction?

  • No

Q13 - Has there been mineral extraction in the past?

  • Not known

Q14 - Are there SSSI/GCR sites here?

  • No

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

  • No

Condition

Q16 - Value

  • High
    • Relatively few notable sites/landforms recorded and geology presumed to be widespread.

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 significant geological or geomorphological features are lost or damaged (e.g. due to development/forestry etc) and that RIGS/SINC are formally established to safeguard key geological/geomorphological features or sites.

Q22 - Guideline

  • Medium Term
    • Ensure that RIGS/SINC are formally established to safeguard key geological/geomorphological features or sites.
  • Long Term
    • Ensure that no significant geological or geomorphological features are lost or damaged (e.g. due to development/forestry etc).

Tolerance To Change

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

  • No

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, 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, aerial photographs, OS 1:25,000 Landranger topographical map.

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

  • 1:25,000

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

  • Breaks of slope at base of solid geology massif/ junction with drift-filled valley system below and base of higher escarpment above.

Evaluation

Q29 - Evaluation Criteria: Research Value

  • High
    • Relatively few notable sites/landforms recorded and geology presumed to be widespread.

Q29a - Evaluation Criteria: Educational Value

  • Moderate
    • Relatively few notable sites/landforms recorded and geology presumed to be widespread.

Q30 - Evaluation Criteria: Historical Value

  • Low
    • Relatively few notable sites/landforms.

Q31 - Evaluation Criteria: Rarity / Uniqueness

  • Low
    • Relatively few notable sites/landforms recorded and geology presumed to be widespread.

Q32 - Evaluation Criteria: Classic Example

  • Low
    • Relatively few notable sites/landforms recorded and geology presumed to be widespread.

Q33 - Evaluation Criteria: Overall Evaluation

  • High
    • Relatively few notable sites/landforms recorded and geology presumed to be widespread.

Q34 - Justification of overall evaluation

  • Relatively few notable sites/landforms recorded and geology presumed to be widespread.

Bibliography

Q35 - Sources and additional assessments

  • DAVIES, J. 2006, Gwent Geodiversity Audit (Report to CCW); INSTITUTE OF GEOLOGICAL SCIENCES 1974, Monmouth, Sheet 233 (1:50,000), NERC; ORDNANCE SURVEY 2005b, OS Explorer Map OL14 (1:25, 000); WELCH, F.B.A. and TROTTER, F.M. 1961, Memoir of the Geological Survey, England and Wales, Sheets 233 and 250.

Assessment

Q36 - Additional Assessments

  • Gwent Geodiversity Audit (Davies 2006): Sites R108/638 (c.SO 443087)?; R109/065 (SO 441132); R110/067 (SO 438130 - SO 437116); R111/068 (S0 438121); R115/63 9 c.SO 420072-SO 426081); R134/229 (SO 35150995); R113/077 (SO 424138); Pant Quarry R114/079 (SO 421138) (Slurian: Pridoli).

Q37 - Additional Comments

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