File:EGS Ballachulish Photo 04.jpg

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Summary

View of the Beinn a' Bheithir massif underlain by the Ballachulish Igneous Complex and Aureole, taken looking south across Loch Leven from the Onich shore near Stop 1-1.

The hill complex seen is referred to Collectively as Beinn Bheithir and the peaks of Sgorr Dhearg and Sgorr Dhonuill form the highest parts of this complex. To the right of the Ballachulish bridge one looks up into the valley of Gleann Chaolais. bounded on the right (west) by the rounded flank of Creag Ghorm (758 m), and on the left (east) by a ridge leading from the rounded shoulder of Meall a' Chaolais up to the slimy) white peak of Sgorr Dhearg (1024 m). At the head of Gleann' a' Chaolais and to the right (west) of Sgorr Dhearg is Sgorr (1001 m) and its subsidiary peak in the foreground, the Devil's Tooth, which forms a prominent cliff-rimmed triangular peak overlooking the head of Gleann a' Chaolais. To the left (east) of Sgorr Dhearg is another more rounded, white peak (unnamed) with a ridge leading down to the rounded shoulder of Beinn Bhan the latter separated from the Sgorr Dhearg ridge by Coire Giubhsachain.

The eastern contact of the Ballachulish igneous complex with the host Dalradian metasediments is subparallel with the lower part of the Meall Chaolais - Sgorr Dhearg ridge, but was obliquely across it in the grassy portion of the ridge just above Meall a' Chaolais, so that it lies on the nearside of the Sgorr Dhearg summit. Interbedded metapelitic, quartzitic and calcareous layers of the Appin Group give rise to the generally more angular exposures along the upper parts of the Meall a' Chaolais– Sgorr Dhearg ridge. The while peak of Sgorr Dhearg itself and the white outcrops along the Beinb Bhan ridge up to the unnamed top to the left (east) of Sgorr Dhearg are formed by Appin Quartzite. On the right-hand (west) side of the mountain panorama, the boundary of the igneous complex lies between Creag Ghorm (on the photo) and the next hill (off the photo to the west).

Thus most of the ground across the loch is underlain by rocks of the Ballachulish Igneous Complex, which gives rise to generally rounded outcrops. Most of Creag Ghorm and Meall o'Choalais are occupied by various varieties of monzodiorite and quartz diorite (see Coloured Map), the earliest of two main phases of the igneous complex. The second phase of granitic rocks, which were emplaced into the diorites in the central parts of the complex, form Sgorr Dhonaill, the Devil’s Tooth and the upper more southerly parts of Creag Ghorm (hugely oat of sight).

Photo 4. From: Pattison, D.R.M. and Harte, B. The Ballachulish Igneous Complex and aureole: a field guide. Edinburgh : Edinburgh Geological Society, 2001.

Licencing

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current21:51, 3 November 2015Thumbnail for version as of 21:51, 3 November 20151,400 × 873 (589 KB)Scotfot (talk | contribs)View of the Beinn a' Bheithir massif underlain by the Ballachulish Igneous Complex and Aureole, taken looking south across Loch Leven from the Onich shore near Stop 1-1. The hill complex seen is referred to Collectively as Beinn Bheithir and the peaks...