Birnam Hill Quarry (proposed)

Local Geodiversity site | Perth and Kinross

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The right of access does not extend to quarries, building sites or any land where public access is prohibited, or to the collection of geological samples.

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Summary

Birnam Slate and Grit formations of the Southern Highland Group of the Dalradian. Impressively large overturned fold in Birnam Slate, part of the Steep Belt related to the Highland Border Downbend.

Birnam Hill Quarry is located within the Steep Belt of the Tay Nappe. Metamorphic grade is low and the bedding, clearly visible from a distance, defines a large-scale antiform with axial planar cleavage dipping northwest. Regional mapping shows the succession is inverted. The main rock types are purple and greenish-grey pelites, generally quite massive, with some laminae and thin beds of silt, a few of which show grading. There is attractive quartz, pink feldspar and chlorite mineralisation associated with small faults.
This is one of the most accessible of a series of quarries in the Birnam Slates just north of the Highland Boundary Fault. The stone, worked from the end of the 18th century to the early 20th century, yielded generally small roofing-quality slates and was also used for walling (many examples in Birnam and Dunkeld). Waste material from some of the other local slate quarries is currently being reprocessed for road metal for the dualling of the A9.

Site information

Access notes

At the foot of Birnam Hill: parking beside the B867 at NO041404. Access by gravel road, under the railway bridge, bear right, turn off core path to left and follow zigzags up hill to quarry.

Further information

Rose, P. 2015. Excursion 18 Dunkeld and Little Glen Shee. In: Browne, M.A.E. and Gillen, C. A Geological Excursion Guide to the Stirling and Perth Area. Edinburgh Geological Society, 232pp.

Shackleton (1958) used evidence from this area to develop the concept of downward-facing folds.
Shackleton, R.M. 1958. Downward-facing structures of the Highland Border. Quarterly Journal of the Geological Society of London 113, 361-392.

Safety notes

The quarry face is dangerous with recent rockfall. Tectonic structures can be viewed from a distance; sedimentary features can be seen in loose blocks.