Peniel Heugh

The microgabbro crags below the Waterloo Monument on Peniel Heugh NT 653 262

The microgabbro crags below the Waterloo Monument on Peniel Heugh NT 653 262

Peniel Heugh is a popular place to visit primarily for the impressive 45m (150 ft) Waterloo monument that was erected between 1817 and 1824 to commemorate the Battle of Waterloo and for the spectacular views over the Border Region afforded even from the base of the monument. The 237 m (791 ft) hill is also the site of a Iron Age settlement.
Walks are described from the nearby Harestanes Visitor Centre but we parked in a space by one of the tracks on the western side of the hill on the small road that heads north to Maxton from the B6400 that heads east from Ancrum to Nisbet.

Map showing locations and rock types around Peniel Heugh

Map showing locations and rock types around Peniel Heugh
Key to map showing locations and rock types around Penielheugh

The microgabbro. that was intruded as a volcanic plug at Peniel Heugh has, like the microgabbro at Dunion Hill, a tendency towards a trachytic texture in which plagioclase crystals are similarly oriented along lines of flow. However, in the samples that we collected at Peniel Heugh, we see a larger gain size than we see in the Dunion hill rock as well as a greater number of augite phenocrysts. This difference may be actual or merely apparent as a consequence of our (under) sampling.

Olivine microgabbro, Peniel Heugh. Thin section viewed with crossed polarising filters (FoV 16 x 10 mm)

Olivine microgabbro, Peniel Heugh
The distribution of minerals in the rock viewed in thin section with crossed polarising filters (FoV 16 x 10 mm)

South-western outcrops of the intrusion

Microgabbro, Peniel Heugh. Exposures close to the south-western limit of the intrusion NT 652 258

The microgabbro exposures close to the south-western limit of the intrusion at Peniel Heugh NT 652 258

Microgabbro Peniel Heugh NT 652 258. Prepared hand specimen viewed in ordinary reflected light (measures 42mm across)

Microgabbro Peniel Heugh NT 652 258
Prepared hand specimen viewed in ordinary reflected light (measures 42mm across)

Microgabbro, Peniel Heugh Thin section viewed in plane polarised light

A thin section from the same sample of microgabbro viewed in plane polarised light

Microgabbro, Peniel Heugh Thin section viewed with crossed polarising filters

The same section viewed with crossed polarising filters

Microgabbro, Peniel Heugh Section viewed in plane polarised light (FoV 4.6 x 3.0 mm)

Microgabbro, Peniel Heugh
Section viewed in plane polarised light (FoV 4.6 x 3.0 mm)

Microgabbro, Peniel Heugh Section viewed with crossed polarising filters (FoV 4.6 x 3.0 mm)

The same area of the section viewed with crossed polarising filters
(FoV 2.3 x 1.5 mm)

Chlorite, magnetite and apatite in the Peniel Heugh microgabbro. Section viewed in plane polarised light ((FoV 2.3 x 1.5 mm)

Microgabbro, Peniel Heugh
Plagioclase, pyroxene, chlorite, magnetite with a few long crystals of apatite in the Peniel Heugh microgabbro. Section viewed with crossed polarising filters (FoV 2.3 x 1.5 mm)

Plagioclase, pyroxene, chlorite, magnetite with a few long crystals of apatite in the Peniel Heugh microgabbro. Section viewed with crossed polarising filters (FoV 2.3 x 1.5 mm)

The same area viewed with crossed polarising filters

Outcrops to the west of the intrusion

Microgabbro crags below the Waterloo Monument on Peniel Heugh NT 653 262

Microgabbro crags below the Waterloo Monument on Peniel Heugh NT 653 262

Microgabbro. Peniel Heugh NT 652 258 Prepared hand specimen viewed in ordinary reflected light (measures 45mm across)

Microgabbro. Peniel Heugh NT 652 258
Prepared hand specimen viewed in ordinary reflected light (measures 45mm across)

Microgabbro. Peniel Heugh. Section viewed in plane polarised light

Microgabbro, Peniel Heugh
Section viewed in plane polarised light

Microgabbro, Peniel Heugh. Section viewed with crossed polarising filters

Microgabbro, Peniel Heugh
Section viewed with crossed polarising filters

Flow arrangement of plagioclase crystals Section viewed in plane polarised light (FoV 4.6 x 3.0 mm)

Flow arrangement of plagioclase crystals
Section viewed in plane polarised light (FoV 4.6 x 3.0 mm)

Flow arrangement of plagioclase crystals Section viewed with crossed polarising filters (FoV 4.6 x 3.0 mm)

The same trachytic texture viewed with crossed polarising filters

Plagioclase, twinned pyroxene, olivine and opaques Section viewed with crossed polarising filters (FoV 2.3 x 1.5 mm)

Plagioclase, twinned pyroxene, olivine and opaques
Section viewed with crossed polarising filters (FoV 2.3 x 1.5 mm)

Plagioclase, pyroxene, olivine and opaques Section viewed in plane polarised light (FoV 2.3 x 1.5 mm)

Plagioclase, pyroxene, olivine and opaques
Section viewed in plane polarised light (FoV 2.3 x 1.5 mm)

Plagioclase, pyroxene, olivine and opaques Section viewed with crossed polarising filters (FoV 2.3 x 1.5 mm)

The same area viewed with crossed polarising filters

Two types or phases of olivine alteration products. Section viewed in plane polarised light (FoV 1.2 x 0.8 mm)

Two types or phases of olivine alteration products
Section viewed in plane polarised light (FoV 1.2 x 0.8 mm)

Two types or phases of olivine alteration products. Section viewed with crossed polarising filters (FoV 1.2 x 0.8 mm)

The same area viewed with crossed polarising filters

The quarry to the west of the monument

Quarry close to the western limit of the microgabbro intrusion, Peniel Heugh NT 653 261. This may have been the source for the microgabbro element of the Waterloo monument

Quarry close to the western limit of the microgabbro intrusion, Peniel Heugh NT 653 261.
This may have been the source for the microgabbro element of the Waterloo monument

Microgabbro, Peniel Heugh NT 652 261. Prepared hand specimen viewed in ordinary reflected light (measures 42mm across)

Microgabbro from quarry at Peniel Heugh NT 652 261.
Prepared hand specimen viewed in ordinary reflected light (measures 42mm across)

References

MacAdam A.D., Clarkson E.N.K., Stone, P. (editors) 1993 Scottish Borders geology: an excursion guide. Edinburgh, Scottish Academic Press.

BGS online Geology of Britain http://mapapps.bgs.ac.uk/geologyofbritain/home.html

No vestige of a beginning, – no prospect of an end

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