Geological Case Study: Coalsnaughton, Clackmannshire

I am an engineering geologist by trade but one of my hobbies is research into the mining history of places of interest. This blog, which is fairly new, will contain several case studies that I am working on, such as the story of the Anglesey Coalfield, which most people don't even know exists, and the mining history of Robroyston in the suburbs of Glasgow and likely several others (send in your request if you want me to have a look at anything specific and I'll see if I think it's a worthwhile case study). My interest was peaked when I learned about the evacuations of people from their homes in the village of Coalsnaughton in Clackmannanshire in May 2026, so I thought I'd have a look at what might have been going on there, but the village has a long history of coal mining, with more industrial scale coal mining starting in the early 1800s. DISCLAIMER: This article is only intended for educational purposes ONLY and not to be reproduced or relied upon by professional mining engineers.

Just to set the scene, let's show you where Coalsnaughton is located in Scotland:

To start with, let's set the geological scene. The village of Coalsnaughton sits on Glacial Till from the last ice age (so typically clay with sand, gravel, cobbles and boulders), but the residential estate that was evaculated is bounded by two streams, which according to geological maps, apparently cut through the till and into bedrock. To the north of Alexandra Street, Tidal Flat deposits consisting of silt and clay are mapped.

The bedrock falls under Scottish Lower Coal Measures and there are numerous coal seams that underlie the village. You can see the generalised vertical section of the Lower Coal Measures in the image below, but as we will see as you move down this article that we know that Coal Mosie, Alloa Cherry Coal and Alloa Splint Coal outcrop within the village, i.e. those coal seams are right beneath the ice age sediments. The Coalsnaughton Main Coal also outcrops not far from the residential estate, just a few meters north.

County Series geological map of Coalsnaughton dated 1878 . Source: BGS Mapping Portal.

Where you often find more detail is on the more modern National Grid 1:10,000 series NS99NW sheet geological map from 1964, from which I showed you the generalised vertical section above.

BGS National Grid Series geological map of Coalsnaughton from 1964. Source: BGS Mapping Portal.

On this map we can see that they've recorded 4 different coal seams in the stream east of The Glen; 0.15m Coal and a 0.25-0.46m coal which is unnamed but shown in the same location as the Coal Mosie on the County Series map. However, on the geological vertical section, the Coal Mosie is shown as 0.76m thick. Looking north, the next coal is the Cherry Coal with a thickness of 1.27m, which according to the vertical section sits beneath the Coal Mosie, followed by the underlying Splint Coal 0.61m in thickness.

On this map, there are also a few additional shafts compared to the County Series, marked with a circle with a cross through it, as well as adits where there were portals for tunnels going into the mines. If you now put your geological hat on, and do some trig of the elevation where the Splint seam outcrops and take your dip angle , once at Benbuck View, you'll find yourself some 5 to 24m higher up in the rock, so at 32.9-51.9mAOD, depending on whether you believe the County Series dip magnitude (gently dipping near horizontal) or the National Grid Series (5 degrees). The ground elevation at Benbuck View is 45.8mAOD, but I know that the National Grid series are exaggerating the dip magnitude, because mine plans exist showing the Splint coal mined beneath the entire residential estate, as you will see further down.

The National Grid Series map suggests a slightly more north-westerly dip direction compared to the Count Series, and gives a dip magnitude of 5 degrees. Now, normally you'd look at the position of the coal seams and note in what order they appear. If they were dipping to the north or northwest, you'd typically expect the older seam (lower down in the stratigraphic column) to outcrop furthest to the southeast. However, here that is not the case and the reason being that there's a fair bit of natural gradient towards River Devon. This is why we see the highest seam in the south. The seams are located at the following elevations where they outcrop in the stream:

• 6" seam is at 55.8mAOD,

• Coal Mosie at 49.5mAOD,

• Cherry at 36.2mAOD; and finally

• Splint at approximately 27.9mAOD.

Taking into consideration the dip angle and dip direction, the elevation of the coal seams rises as you go southeast, though so does the natural terrain, whose gradient is about 4.7 degrees.

There is a mine plan that shows the distances between each of the seams:

• Mosie Coal to Cherry (Lower Five Foot) 7.5 fathoms (13.7m),

• Cherry/Lower Five Foot to Splint 3 fathoms (5.5m) and

• Splint to Coalsnaughton Main 12.5 fathoms (22.9m) - though it's 18m from Split to Wallsend, which was often extracted alongside the Main.

Snippet from mine abandonment plan with modern OS Streetmap below (Source: The Mining Remediation Authority)

The concerning part here is that just next to the blue coloured mine workings in the Splint Coal within the residential estate, there's a text stating "Old waste", which is where the miners stopped back in 1832 as they encountered ancient workings backfilled with mine waste. The issue with these type of ancient mines is that no record exists of their location, and it is very rare that someone would go at a later date to survey them because they'll be very dangerous and/or inaccessible due to either collapse of the roof of the mine or backfill material. A similar thing is shown on the Coal Board plan of workings in the Splint Coal, which I have georefenced and included below, but you can find the originals on the Scotland's People archives. Here, the recorded mine workings are shown in red ("unrecorded" are workings such as those shown as "waste" or where the mine workings have not been seen or surveyed).

Georeferenced and merged plans of Alloa Splint mine workings in Coalsnaughton with reference 26/9095, 26/9096, 26/9295 and 26/9296. (Source: Scotland's People).

Mine workings in Coalsnaughton Main Coal

We have already discussed the locations of the coal outcrops, the thickness of the seams, the vertical distance between the seams and the fact that the highest worked seam, the Splint, has been worked extensively in the area from ancient times. The Coalsnaughton Main Coal has also been worked extensively in the area, as shown in the four plans I have georeferenced and merged together below.

Georeferenced and merged plans of Coalsnaughton Main mine workings in Coalsnaughton with reference 26/9095, 26/9096, 26/9295 and 26/9296. (Source: Scotland's People).

On the plan you'll see lots of mineworkings of different ages. The oldest recorded one is the one beneath Coalsnaughton, with two "Old Shafts" used to access those workings and the edges of the mine workings shown dated 1857 and 1862. The Crankie Shaft, which also appears to intersect the workings, is shown as "Filled ip prior to 1961". There are yet older workings just to the east of those mine workings where it says "Waste" where the miners back in the mid 1800s must have decided not to go into (likely no access and probably not safe either). There are also more ancient workings just to the south of the 1800's workings, but parts of them were surveyed, as stated on the plan: “Old workings surveyed 5th May 1949”. Looking at these, it gives us an indication of the type of workings they were, traditional room and pillar workings where the extracted rooms were about 3m wide and the pillars somewhat variable but many I measured to be about 8m wide. The problem with pillar and stall workings is that the pillars can degrade over time and if they eventually collapse, then they can cause delayed subsidence (normally subsidence would happen more or less as soon as the seams were worked, particularly when no pillars were left in place).

Then to the east of Coalsnaughton, you can see a similar pillar and stall pattern of workings, where the coal was extracted in the early 1900s still by traditional means, but about a decade later they seem to have moved onto total extraction, where no pillars were left in place (shown as all shaded red. Then the workings furthest to the west have been mined using the more modern and industrial scale longwall mining, where everything was taken out across panel shaped areas. There are some good seam records of seam levels for those workings (level is based on 10,000 feet above ordnance datum - so if the number is lower than 10,000 feet then the level is that many feet below ordnance datum).

Snippet of the generalised vertical section from BGS 10k geological map NS99NW showing bedrock beneath Coalsnaughton.

Here you can see that the Coal Mosie is 0.79m in thickness, the Cherry Coal is 1.27m, Splint Coal is 0.61m and the Coalsnaughton Main Coal is 1.07m in thickness. However, thicknesses of the individual coals will vary regionally. Seeing as these outcrop within the residential estate, it is safe to say that any mineworkings in these seams would be very shallow.

When I look into the mining history of a place, I tend to trust the older geological maps better. Much of the reason why so much money and time was spent on mapping the geology back then was for the record of economic minerals. Therefore, it's safe to assume they wanted to keep good records of where these economic seams were to be found.

The County Series geological map from 1878 shows the Coal Mosie to outcrop in the stream that runs along The Glen in Coalsnaughton immediately to the east of the village. The symbology on the map shows the strata to dip very gently, near horizontal, in a northerly direction. The map also shows us the location of a couple of coal pits in the vicinity of the village - one between modern day Ochil View and Bain Street, the other near The Devon Way as it turns away from Alexandra Street towards the River Devon.

A snippet from the 1878 map is shown below, overlying a modern OpenStreetMap layer.

Mine workings in the Splint Coal

It is known from mine plans that the Splint seam has been worked extensively, possibly completely exhausted, in this area. The Coalsnaughton Main has also been extensively mined, often along with the Wallsend at the same time. There is little evidence to suggest that the Cherry/Lower Five Foot or Mosie have been extracted, but given the fact that they are of workable thickness (usually seams that are 0.3m in thickness or more), it is not possible to rule out that maybe that seam has been extracted here as well. So you can see there could be a problem if your house is sitting right above the Cherry outcrop, with Splint worked so very shallow below.

This takes us to the mine plans showing the mine workings in the Splint Coal, which is the shallowest seam in this area known to have been worked. The mining that took place in the early to mid 1800s is shown in blue below. There is a dark blue linear feature where it says "Level" leading from the Split seam outcrop by River Devon. This is an access tunnel to the mine, with the tunnel portal located on the southern banks of the river.

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