Stac Pollaidh

Ascent — around 600 metres

Difficulty — moderately strenuous ascent on a good path

Duration — 3 – 4 hours circular walk

Start — grid reference [NC 107 095]

The ascent of Stac Pollaidh (613 metres) is a relatively short walk on a good path, but it climbs steeply in places. Most people should be able to reach the ridge, where the views are stunning, but the true summit is more tricky, requiring an exposed scramble, and its ascent is only for hillwalkers with scrambling experience. Warm clothes and good boots are needed at any time of year, since the weather in this area can change rapidly.

Stac Pollaidh, one of the most popular hills in Scotland, is built from Torridonian Sandstone and conglomerate, deposited as sand and pebbles in rivers about 1000 million years ago. Looking up from the car park at the foot, you can see the jagged rock pinnacles that crown the summit ridge, rising from scree-covered lower slopes. Exposure to the harsh Scottish climate, together with the pounding of many feet, has caused Stac Pollaidh to crumble.

From the car park the path ascends past a stand of birch trees. Bear right at the path junction just before the deer fence [1] [NC 10868 09984]. The old route used to go straight up to the summit, but now a new path ascends round the east flank of the hill, causing far less erosion. The lower slopes of Stac Pollaidh are covered in scree, much of it formed after the end of the last ice age and now vegetated. The scree forms when rain water seeps into small cracks in the sandstone, and is repeatedly frozen and thawed. This process prises apart and loosens blocks of rock, which then tumble down the slopes.

Below the great rocky buttress at the eastern end of the summit ridge, the path crosses a boggy area and then ascends some rocky steps [2] [NC 11285 10395]. This is a good place to have a look at cross-bedding in the red-brown sandstone. Layers of fine sandstone alternate with coarse gritty layers, and if you trace the layers you can see that they curve upwards to be cut off by higher ones. This cross-bedding was formed as large ripples on the sandy bed of an ancient, fast-flowing river (see box on page 5).

Rounding the eastern flank of Stac Pollaidh, the view to the north is dominated by the Torridonian Sandstone peaks of Suilven and Cùl Mòr. The terrain at the foot of the mountains is a hummocky surface of Lewisian Gneiss dotted with lochs. A continuous sheet of Torridonian Sandstone, several kilometres thick, once extended across this entire area. Over the past two million years, glaciers have scoured the landscape and exploited valleys through the sandstone, deepening and widening them to leave the isolated peaks standing proud.

Take a left turn at a fork in the path, and head up towards the summit ridge. Climb through scattered outcrops to a col on the ridge, where fantastic views to north and south await [3] [NC 10932 10541]. The cross-bedded sandstone on the ridge of Stac Pollaidh has been weathered and eroded into weird and wonderful pinnacles and towers. Exposure to the elements over thousands of years has resulted in disintegration of the sandstone along cracks and fissures. Winds, armed with sand, continually abrade the more exposed rock faces. If you happen to be here on a windy day and sit on the ridge, you may feel the sting of sand blasting your face. Stac Pollaidh has been exposed to such sandblasting for millennia.

From the col, it is possible for those with a good head for heights to turn right and make their way to the summit of Stac Pollaidh along the western ridge. There is no single path towards the top: several smaller paths traverse just under the rocky towers, all involving some scrambling. Reaching the highest summit involves an exposed scramble over a rock tower, not recommended for those without scrambling experience and the appropriate footwear. Most walkers will prefer to turn left at the col and take the short ascent to the eastern peak, from where there are wonderful panoramic views.

Formation of sandstone pinnacles through weathering

1. Rainwater seeps into cracks and fissures in the sandstone.
2. As the water freezes and thaws, the cracks are widened, forcing blocks of sandstone apart.
3. Loose blocks fall, leaving behind rock pinnacles that are further sculpted by wind and rain.

Return to the col and take the downward path a few metres west of the point where you reached the ridge, descending westwards along a path that passes above a fenced area. This brings you down to a path that encircles the hill. Turn left on this path to descend round the western slopes. From here, there are fine views towards the Point of Stoer, and on a clear day, across to the Western Isles. After a few hundred metres, as you approach a lochan, you pass through a jumble of huge blocks [4] [NC 10641 10882]. This is a rockfall, formed when part of the north-west wall of the buttress above collapsed. The large size of the lichens growing on these boulders indicates that the rockfall is several thousands of years old.

As you continue around the western buttress of Stac Pollaidh you see, just to the left of the path, another much larger pile of huge boulders forming a ridge or rampart [5] [NC 10367 10439]. These boulders must also have fallen from the face of Stac Pollaidh, but they were probably banked up against the margin of a glacier that once occupied the valley now containing Loch Lurgainn. When the glacier melted, the rocks were left as a ridge on the slopes of the hill. From here, follow the path through the boulders and scree down to the deer fence, and join the path back to the car park.

Figures

(Figure 58) Stac Pollaidh.  Painting of walk by Elizabeth Pickett.

(Figure 59) Stac Pollaidh from the north shore of Loch Lurgainn. Painting.

(Figure 60) Cross-bedding in Torridonian Sandstone on the Stac Pollaidh path.

(Figure 61) Sculpted sandstone on the ridge of Stac Pollaidh.

(Figure 62) Cross-bedded sandstone pinnacle on the ridge of Stac Pollaidh.

(Figure 63) Formation of sandstone pinnacles through weathering (painting).

(Figure 64) Formation of sandstone pinnacles through weathering (photo).

(Figure 65) Boulder ridge on the western slopes of Stac Pollaidh.