View source for Prograde sequence in the Ballachulish Slate along the Gleann a' Fhiodh – Coire Chaorann ridge - an excursion

=== Stop 4-4. Cordierite-rich hornfelses, Zone III. NN 0620 5380, 450m. ===
''Directions: ''From Stop 4-3, cross the steep gulley and the Ballachulish - Glen Creran footpath, and proceed across a level area with little exposure. As the ridge top rises to the WSW, follow the north-facing side of the ridge (going obliquely uphill, roughly parallel to the ridge top), where there are numerous good exposures of cordierite-spotted hornfelses, sometimes interlayered with more psammitic rocks and commonly showing small scale folds and locally strong crenulation cleavage. As one goes upgrade, the cordierite-spotted rocks become harder and less fissile, although crenulated cleavage surfaces are still obvious. Continue going uphill around the hillside until the slope faces NW (close to the ridge top), where there are good exposures below which lie many angular boulders.

''Description: ''The exposures contain cordierite-pitted, crenulated grey phyllite with folds of bedding and cleavage. These contain the characteristic Zone III assemblage Ms+Crd+Bt+Qtz. but compared to Stop 4-3 the rocks are more indurated.