Earlier this summer a friend of mine and I did the (probably) most famous long distance hiking trail in Scotland: The West Highland Way. This 154 km long route through the western highlands is traditionally walked from South to North, with the start located in Milngavie just north of Glasgow and the finish is Fort William. With about 30.000 people walking the whole way each year the trail is quite busy. To avoid walking in a larger group of strangers we decided to walk from North to South. While the record time for completing the Way is less than 16 hours, we decided to take a more relaxed approach and aimed to finish it in seven days. Additionally, we avoided camping and stayed in hostels and bunkhouses (not only because we did not want to carry around a tent and camping equipment but also because we had been warned of severe rains and midges). The stages were:
- Fort William to Kinlochleven (23 km)
- Kinlochleven to Kingshouse/Glen Coe (15 km)
- Kingshouse to Bridge of Orchy (21 km)
- Bridge of Orchy to Crianlarich (21 km)
- Crianlarich to Inversnaid (21 km)
- Inversnaid to Balmaha (22 km)
- Balmaha to Milngavie (32 km)
The stages look quite short, but for untrained hikers its perfect. You can enjoy your breakfast and normally arrive with loads of time for showers, dinner and drinks (6-7h per stage, except for the last one which took forever). But be aware of blisters, they are more evil than one might think and can make walking a living hell.
The aim of this blog entry is not to give advice on what to do and what not to do during the hike but to give an overview of the landscape and geology one can experience when walking the way. However, some things that might be of interest are:
There is no cheap accommodation at the end of the second stage at Kingshouse (depends on what you think is cheap though). We took the city link bus (914) from the Glencoe ski resort to Glencoe village and stayed the night at glencoe hostel. While the hostel is cheap, the bus ride is quite expensive (7£ one way p.p.) and the hostel is at least 2.5 km from the nearest bus stop (not < 1 mile as they state!). On the upside dinner at the Clachaig Inn is really good!
There really are no free cash machines between Fort William and Milngavie. So if you don’t want to pay extra fees bring enough cash. And don’t rely on plastic money (bank cards) as sometimes places do not have cash free payment yet (dooh!).
Scotland as it exists today can be geologically divided into five terranes, fragments of the earths crust, that have been sutured together when different tectonic plates collided in the past (similar to the continent-continent collision of Africa and Eurasia that formed the Alps). All five terranes have a different geological history and the rocks we can observe at the surface often formed deep within the earth’s crust. For example rocks of Lewisan complex within the Herbridean Terrane have originally formed in depths of several 10s of kilometers more than 2.7 billion years ago and have been subsequently buried to even deeper depths and can today be found at the surface! The suture zones where the terranes adjoin are major fault zones. Due to the massive stress the rocks in fault zones undergo they are often structurally weaker than the rocks located in the centre of terranes and if exposed at the surface they erode quickly. The Great Glen Fault Zone is a very good example for this: Erosion during the last glaciations led to a long valley (the Great Glen) with several Lochs including the famous Loch Ness. The starting point (or the finish..) of the West Highland Way, Fort William, is located within the Great Glen.
Starting within range of vision to rocks of the Moine Supergroup of the Northern Highland Terrane the West Highland Way leads through rocks of the Dalradian Supergroup of the Grampian Highland Terrane to rocks of the Old Red Sandstone and younger in the Midland Valley. Between the formation of oldest (Moine) and the youngest (Carboniferous) rocks more than 500 million years passed!
The rocks of the Dalradian Supergroup consist mainly of sediments that were deposited in shallow to deep marine environments. The sediments were deeply buried and deformed during the Caledonian orogeny and are now metasediments (metamorphic sediments). The correlation and dating of metasedimentary rocks is, in my eyes, one of the most challenging and complex fields of study for a geologist. No wonder I keep to normal sediments! Below you can see an example of a deformed metasediment of the Southern Highland Group. Note the beautiful colour changes on a small-scale. Similar exposures are frequent on the north-eastern shore of Loch Lomond north of Inversnaid where the slope is quite steep.
Additional to metasediments extrusive and intrusive igneous rocks can be found north of the Highland Boundary fault. Intrusive igneous rocks form within the earth’s crust and can only be found at the surface if the overlaying rocks have been eroded. Extrusive igneous rocks are also known as volcanic rocks and form at the surface of the earth. The first igneous rocks that one can see when walking the West Highland Way belong to the volcanic complex of Ben Nevis, the highest mountain of the British Islands! While there are both intrusive and extrusive rocks, only the former are identifiable from the Way. More exiting is, further south on the WHW, the volcanic complex of Glen Coe! This volcano is a very good example of a caldera formation similar to more recent examples of Yellowstone or Pinatubo. A caldera forms during the late phase of a large volcanic eruption when the land surface collapses into the now empty magma chamber. Not all volcanic eruptions lead a caldera formation. The Glen Coe volcano has had a complicated eruption history over probably more than 500.000 (the whole complex formed about 420 Ma ago) and has been studied by geologist for over 100 years (an Example) and is considered to be one of the best examples for cauldron subsidence. But Glen Coe does not offer only very intriguing geologic features but also a wonderful scenery (see below) and is popular with climbers and hill-walkers alike.
Towards the end of the journey along the West Highland Way (or at the beginning) one leave the Grampian Highlands and enters the Midland Valley. The Highland Boundary Fault separates both terranes and the Old Red Sandstones to the south of the fault are now vertically inclined. This can be observed in a digital elevation model as the conglomerates are more resistant to erosion than the finer grained rocks (the yellow Arbuthnott-Garvock Group in the picture below).
The map also shows that the Highland Boundary Fault crosses Loch Lomond. Several islands have formed where the Old Red Sandstone has resisted erosion. These can be seen from Conic Hill, the last (or first) hill the West Highland Way passes on its way to the South near Balmaha (the islands in the centre of the picture!).
And, how else should I end this post, here, finally (you have been waiting for this haven’t you?!), a picture of the conglomerates. Note that there are fine-grained layers between the clast-supported. I would have liked to put more pictures into this post, but sadly this is the only one that has a proper scale in it (the length of the photo case is 14 cm ;-)). I hope you enjoyed it nonetheless!