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Route plan for Meallan An Laoigh

PostPosted: Fri Apr 12, 2013 1:25 pm
by GravelInspector
This is a specualtive route being planned for examining the geology of the Moine Thrust system in the "Whitbread Wilderness". A friend is considering a trip there.

Spec-1986-Meallan an Laoigh Moine Thrust route.gpx Open full screen  NB: Walkhighlands is not responsible for the accuracy of gpx files in users posts




Strictly, it's the Kinlochewe Thrust that is traversed repeatedly.
The route is figured from road-end to road-end. If a landrover and keys for the gates are available, then one should be able to get somewhat beyond Achnegie House and park up, to approximately halve the total boot wear.

The gate at the Dundonnell road end is always secured (well, I've never seen it unlocked, in 30-peculiar years) ; at the Lochivroan end, it is normally possible to get to the boathouse at the foot of the loch, though I've cracked a road car's sump doing so and don't recommend it.

Much of the landrover track distance is cycleable, but less of the path.

There are no issues getting to the foot of Loch an Nid, from either direction. Coming via the LR track at Achnegie is considerably preferrable, but would need contact with the estate (Dundonnell? or Loch Broom?) to organise keys.

Foot of Loch an Nid : Cambrian quartzites. May be conformable on the Lewisian at the foot of the waterfalls, but I never searched for that, as it was beyond the edge of my mapping area. Considerable thickness of section around the waterfalls. Crossing the river is nerve-wracking.
Up the slopes to Meallan an Laoigh : more quartzites, but you may be able to find slivers of the "Serpulite Grit" and "Fucoid" beds, or even a sliver of limestone as you approach the Meallan. But I only found Lewisian on mylonite on Quartzite. Pseudotachylites at several locations in circuit round the Meallan.
More tedious Quartzites up to summit of Sgurr Ban. As you go up in sequence, frequency of red-brown grit beds seems to increase (in hindsight, I should have sectioned this slope, or the next-but-one), which makes the pipe-rock traces stand out better.
Back down to the Cab Choire nan Clach col (NH052739) cuts through much of the thickness of the Quartzites, or the next slope does 30m more. On the summit of Mullach Choire Mhic Fhearchair there's definitely more of the red-brown/ white quartzite, and lots of nice traces.
Continue along the ridge to SW, going further up Quartzite section, until you reach the thrust plane at about (NH059730). I didn't actually find anything terribly interesting there - rather shattered - but there are more pseudotachylites and mylonites exposed on the S flank. The N flank looked too loose for my taste, and I saw rockfalls when I was there.
Going broadly east there's the usual "knock and lochan" landscape of the Lewisian, if at rather high altitude. I found some lovely pure-amphibole rocks here - probably "Scourian" dykes.
Cut through a break in the N cliffs (fault? I couldn't see one on the ground) and spend as much time as you don't like crumping down on greasy slabs of Quartzite again. The contacts look well buried in talus on this flank - and rock falls bounce a long way - I did a 1-ton "trundle" across this area, which was only half intentional.
At the foot of the exposed slope of Quartzite is a midge-infested (by W.Highland standards!) gully with the above-Quartzite Cambrian succession exposed in the East wall. Some scrappy "fuciod" fossils, but nothing diagnostic that I found.
Back down the rest of the hill and cross the river above Loch an Nid.

There are visible (I think) lenses of limestones in the craggy ground above-East of the path, but the ground looks really discouraging, slimy and unstable. So I bounded my area at the river.
While I've never done this all in one day, I did spend weeks doing field work in the area, making multiple trips to particular outcrops of this area.