Torduff Hill, Pentlands. Photo: Angus Miller

The excursion aims to examine some of the Lower Devonian basalts and trachytes of the Pentland Hills Volcanic Formation, and rare exposures of rocks of the Kinnesswood and Ballagan formations (Carboniferous). The geological foundations for the local reservoirs of Torduff and Clubbiedean will be discussed.

Read the Code of Conduct and Safety Guidelines and book your place …

Excursion title:

Bonaly

Date & time:

Wednesday 9 May 2018, 7.00pm

Finish time:

9.00 pm

Leader:

Andrew McMillan, Lothian & Borders GeoConservation

Excursion aims and description:

The excursion aims to examine some of the Lower Devonian basalts and trachytes of the Pentland Hills Volcanic Formation. Rare exposures of rocks of the Kinnesswood and Ballagan formations (Carboniferous) may also be seen. The geological foundations for the local reservoirs of Torduff and Clubbiedean will be discussed.

Transport:

Lothian Bus No. 10 either to Torphin (alight in Woodhall Road at junction with Bonaly Road) or to Bonaly and alight at Bonaly Corner Shop (terminus). Walk up Bonaly Road to meeting point (below)

Meeting point:

Meet at 7.00 pm at the roadside car park on south side of Bonaly Road bridge over the A720 Edinburgh Bypass [NT 213 679] (there is no exit/slip from Bypass onto Bonaly Road; the nearest is Redford slip). Return to Bonaly Road bridge by 9.00 pm.

First locality:

Roadside car park on south side of Bonaly Road bridge over the A720 Edinburgh Bypass [NT 213 679] (there is no exit/slip from Bypass onto Bonaly Road; the nearest is Redford slip).

Excursion route:

Circular route around Torduff Reservoir. The walk goes firstly to the west end of Torduff Reservoir [NT 206 677] and then to the dam of Clubbiedean Reservoir before returning via Torduff Hill and the track leading north past Bonaly Tower.

Terrain, walking distance, height gain:

Total distance of 5 km is mainly on good tracks; some heathery moorland. Wear walking boots. Walking poles may be of assistance.

Specific or Medium- / High-Risk Hazards:

Walking on single track road with occasional traffic, and grassy or stoney public footpaths; some short moderately steep ascents and descents.

Control measures required to mitigate against any Hazards referred to above:

Be aware of traffic; take care on paths which may be slippery especially in wet weather

Hard hats or Hi-viz clothing needed?

No

May dogs be brought on the excursion?

Dogs may be brought provided they are kept on leads.

Toilet information:

Nearest public toilets in Colinton Village

Geological map sheet:

BGS 1: 50 000 32E Edinburgh

OS map sheet:

OS 1:50 000 sheet 66 Edinburgh, Explorer sheet 350

References:

Mitchell, G H and Mykura, W. 1962. The geology of the neighbourhood of Edinburgh. Memoirs of the Geological Survey, Scotland.

Mykura, W. p. 169-173 in McAdam, A D and Clarkson, E N K.1986. Lothian Geology – an Excursion Guide (Edinburgh Geological Society).

Sivasubrammaniam, A and Carter, V F. 1969. Investigation and treatment of leakage through Carboniferous rocks at Clubbiedean Dam, Midlothian Scottish Journal of Geology, Vol. 5, 208-223.