Aug 202022

First published in: The Times Click here to view a map for this walk in a new window
Achnahaird Bay 1 Achnahaird Bay 7 Achnahaird Bay 2 Achnahaird Bay 3 Achnahaird Bay 4 Achnahaird Bay 5 Achnahaird Bay 6 Garvie Bay 1 Camas a' Bhothain ejecta studded with papilli from the asteroid collision 1.2 billion years ago stromatolite in the middle foreground - Europe's oldest life form otter at play otter at play 2 drinker moth caterpillar? Stac Pollaidh beyond the Garvie bridge

The rugged peninsula of Coigach in north-west Scotland is famous for its wild beauty and its geological treasures. Peter Drake, sea fisherman and our companion on this walk, was a prime mover in establishing the 45-mile Coigach Geotrail round the shores of the peninsula.

Orange bladder wrack lay draped on the slabs of ancient red sandstone fringing Achnahaird Bay. Cast up here we found a knob of Lewisian gneiss, banded in pale and dark grey, three thousand million years old. This rock was formed when the Earth’s crust had not even properly solidified.

On the grassy headland an otter was leaping and bounding, a lithe shape full of energy, suffused with joy in its own existence. Later we saw it rolling on its back in the bay, crunching up a fish held between its front paws.

In the bay of Camas a’ Bhothain stood a ruined salmon bothy. Beyond ran a layer of rock in red-grey sheets pressed close together. ‘The oldest inhabitants of Coigach,’ stated Peter. This very finely layered limestone is a stromatolite, a structure created by microbes that clung to rocks around the shore of a lake some thousand million years ago. It represents the earliest form of life yet discovered in Europe.

On the shore beyond the bay, a smear of red rock told a dramatic story. Around a billion years ago an asteroid measuring half a mile across slammed into the planet at 25,000 miles per hour, a dozen miles away from where we stood. The shock of the impact liquidised the Earth’s crust in the vicinity and spattered it far and wide in a splash of ejecta or molten rock.

Stuck in the ejecta we found greenish fragments of the asteroid itself, and a sprinkling of tiny globules like acne on a teenage face – the spherical lapilli or droplets of molten rock that cooled and hardened as they fell out of the sky from the massive volcanic cloud which billowed up above the site of the strike.

We rounded the corner of the peninsula and found ourselves staring at an eastern skyline clouded but magnificent – the mountains of Inverpolly, horizontally striped sandstone some thousand million years old, all that’s left of the landscape that lay here before the giant glaciers of the Ice Ages scraped most of it away. Cloud filled Inverpolly and streamed in a thin gauze from the tall butte of Stac Pollaidh and the twin horns of Suilven. It was a magnificent spectacle to accompany the homeward hike over bog and heather.

How hard is it? 6½ miles; moderate; rough boggy walking, with boulders and slippery rocks underfoot in places

Start: Loch Raa car park, Achnahaird IV26 2YT approx. (OS ref NC 021123)

Getting there: Bus 811 (Ullapool-Achduart)
Road – Achiltibuie is signed off A835 Elphin-Ullapool road; Loch Raa car park is about 2½ miles north of Achiltibuie.

Walk (OS Explorer 439; downloadable trail map and notes at From Loch Raa car park, head north along west side of Achnahaird Bay, either on shore or along sheep path near cliffs. In 1¼ miles cross deer fence (023142; stile). Follow coast to salmon bothy ruin in Camas a’ Bothain (029145). Continue across neck of Rubha a’ Choin peninsula (034146). Along rocky beach; up headland and turn right to cross deer fence (038142). Continue south down Garvie Bay, then along west bank of river to road bridge (040129). Right for 1½ miles to car park.

Lunch: Picnic from Achiltibuie Stores (01854-622496); Summer Isles Hotel (01854-622282;

Accommodation: Acheninver Hostel (comfortable sleeping pods) – 07783-305776;


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