Aberdare: Coal, memory and the fossil forests beneath

“If there is one type of man to whom I do feel myself inferior, it is a coal-miner.”
— George Orwell, The Road to Wigan Pier

This article explores a single landscape – Aberdare – through three interlocking layers: the Carboniferous forests that formed the coal, the industrial system that extracted it, and the lives lived within that system. Each survives only in fragments: fossils weathering from shale, objects preserved in family memory, and traces embedded in the modern landscape. Taken together, these fragments allow the reconstruction of a place in which deep time, industry and lived experience are inseparable.

Return to Aberdare

Aberdare is no longer a coal town in any functional sense, yet the landscape still bears the imprint of the industry that once defined it. Pitheads have gone. Spoil tips have been reshaped, landscaped, absorbed by vegetation or erased altogether. Footpaths now follow alignments that were once tramways and mineral lines (Fig. 1). For a visitor returning after many years (as I did in March 2026), it is often the absences that are most striking.

Fig. 1. Possible remains of the access route and pit-head area of Gadlys Colliery, near Aberdare. (Top left) the old trackway passing beneath a small road bridge. (Top right) the same route continuing uphill via a substantial flight of stone steps, suggesting it once served regular traffic rather than a simple footpath. (Bottom) a broad, unusually flat area on the hillside, with faint terracing beneath the electricity pylon. Taken together, these features suggest that this level ground may once have formed part of the pit-head complex, with the trackway providing a direct route for miners walking up from Aberdare.

What remains is a terrain that appears quieter, tidier and more orderly than its history would suggest – yet one in which traces of the coalfield persist for those who know how to look. These traces are not only industrial. They sit above a much older landscape: the Carboniferous coal-swamp forests that, over geological time, became the coal itself.

Fig. 2. A carefully fenced off ventilation shaft for the mine.

Objects as witnesses: fragments of a coalfield life

Some of the most direct connections to this landscape survive not in the ground, but in objects.

One is a framed Vanity Fair caricature of Keir Hardie, signed by Hardie and presented to my grandfather in recognition of his support during his successful campaign to be elected MP for Merthyr Tydfil (Fig. 2). It is not a grand historical document, but a modest domestic artefact – a fragment linking one individual life to the wider political transformation of the South Wales coalfield and, ultimately, the whole of Britain.

Fig. 3. Vanity Fair caricature of Keir Hardie, signed (lower right) and presented to the author’s grandfather, linking family history directly to the labour politics of the South Wales coalfield.

Another is a miner’s safety lamp made by E. Thomas & Williams Ltd of Aberdare (Fig. 4). Described as a “Cambrian-type” lamp – using the Victorian term “Cambrian” to mean “Welsh” – it represents the everyday material culture of the coalfield. Its enclosed flame and locked construction were designed to prevent the ignition of methane underground, an ever present hazard in coal mining.

Fig. 4. Miner’s safety lamps made by E. Thomas & Williams Ltd of Aberdare. The darker lamp on the left is an original working example that may have belonged to the author’s grandfather; the polished lamp on the right is a modern lamp made by the same firm. Both are “Cambrian-type” lamps – a traditional South Wales pattern of locked flame safety lamp widely used in Welsh coal mines. Here “Cambrian” simply means “Welsh,” rather than referring to the geological Cambrian period.

Like the fossils described later, these objects are fragmentary survivals. Preserved by circumstance rather than design, they connect the lived experience of individuals to the wider systems – political, industrial and geological – that shaped the coalfield.

A miner’s life, partially recovered

My grandfather – Frederick John Coombes – lived at 9 Hall Street, Aberdare (Fig. 5), and worked as a collier in one of the nearby pits, probably Gadlys Colliery. The terraced streets of Aberdare were built rapidly to house the expanding workforce of the coalfield, forming dense, tightly organised communities within walking distance of the pits.

Fig. 5. Hall Street in Aberdare, lined with late-nineteenth-century terraced houses originally built for coal miners. Although now largely modernised, their uniform layout reflects the rapid industrial expansion of the South Wales coalfield.

At some point, probably when he was still a young man, he was severely injured underground when a roof mass collapsed while he was working in a low seam. Family memory recalls this as the fall of what may well have been what UK miners called a “kettle-bottom” – the fossilised base of a lycopod tree — a reminder that the dangers of mining were rooted not only in engineering, but in the geological structure of the coal measures themselves.

His arm was badly shattered and never healed properly, requiring a leather support for the rest of his life. The injury ended his working life underground, but not his involvement in the coalfield community. He remained active in the coalfield community, particularly in local labour politics, supporting candidates such as Keir Hardie at a time when organised labour was reshaping both the valleys and the country.

Here again, fragments intersect: a fossilised tree base in the roof of a coal seam, an industrial accident, and a signed political cartoon – each part of the same story.

Childhood collecting and first geological connections

My own connection with this landscape began much later, during childhood visits to my grandmother in Aberdare, and walks with my mother across the margins of the former coalfield. The spoil tips – now long gone – were not approached as geological sites, but as places to explore.

It was on these walks that she pointed out living horsetails growing in waterlogged roadside ditches, explaining that these everyday plants provided a direct analogue for the fossil sphenopsids weathering out of the spoil. Even then, without formal understanding, the connection was clear: the industrial debris underfoot contained the remains of a much older, living world.

Only later did I realise that the spoil tips themselves were acting as unintentional geological exposures, bringing together material from multiple levels of the Coal Measures into a single, accessible surface.

The Coal Measures context: the deeper landscape

The same ground that supported mining communities also contains the remains of the ecosystems that made mining possible.

The spoil tips around Aberdare derive largely from roof shales and mudstones above worked seams within the Upper Carboniferous Coal Measures. These sediments record low-lying, waterlogged environments in which sphenopsids – Calamites, Annularia and Sphenophyllum – formed a dominant component of the vegetation, alongside seed ferns and extensive root systems.

When excavated and tipped at the surface, these beds were inadvertently reassembled into a condensed fossil assemblage. A single spoil tip could yield stems, leaves, roots and plant associations normally separated by metres of stratigraphy, offering a fragmented but coherent glimpse of the coal-swamp forests that once occupied this landscape.

Fossil plants from the Aberdare spoil tips

The fossils collected from these spoil tips are modest, often fragmentary, yet together they preserve a consistent ecological picture.

(1) Sphenopsids: Calamites, Annularia and Sphenophyllum

Sphenopsids are particularly well represented. Calamites stems occur frequently (Fig. 6), recognisable by their longitudinal ribbing and regular nodes (see box: What were Calamites?), while detached whorls of Annularia (Fig. 7) record the foliage borne on their branches. Alongside these are repeated remains of Sphenophyllum (Figs. 8-11; and see box: What was Sphenophyllum?), a smaller, scrambling plant whose wedge-shaped leaves form distinctive star-like whorls.

These are not isolated finds. Their repeated association points to a persistent plant community adapted to wet, disturbed ground – exactly the conditions expected on Carboniferous floodplains and swamp margins.

*What were Calamites?*
Calamites were tall, tree-like relatives of modern horsetails and a major component of Carboniferous coal-swamp vegetation. Some species reached heights of 20m or more, with hollow, jointed stems divided by regular nodes. Their surfaces were marked by longitudinal ribs, often preserved as fine vertical striations in shale (Fig. 6). Calamites grew in waterlogged ground along floodplains and channel margins, spreading by underground rhizomes and rapidly colonising disturbed environments.

What were Calamites?

Calamites were tall, tree-like relatives of modern horsetails and a major component of Carboniferous coal-swamp vegetation. Some species reached heights of 20m or more, with hollow, jointed stems divided by regular nodes. Their surfaces were marked by longitudinal ribs, often preserved as fine vertical striations in shale (Fig. 6). Calamites grew in waterlogged ground along floodplains and channel margins, spreading by underground rhizomes and rapidly colonising disturbed environments.

Fig. 6. Fragmentary stems of *Calamites* preserved as low-relief impressions in fine-grained shale from an Aberdare colliery spoil tip. The characteristic longitudinal ribbing and regular internodal pattern are visible despite compaction and fracturing, reflecting the robust, jointed architecture of these arborescent horsetails that once formed a conspicuous element of Carboniferous coal-swamp vegetation. (Scale in cm.)

Fig. 7. Two specimens showing well-preserved radial leaf whorls of *Annularia*, the foliage form-genus of Carboniferous horsetails (*Calamites*). The narrow, elongate leaves radiate evenly from a central node, producing a characteristic star-burst pattern that distinguishes *Annularia* from *Sphenophyllum (see below)*, whose leaves are wedge-shaped and fewer in number. (Specimens about 2cm across.)

Fig. 8. *Sphenophyllum* sp. leaf whorls from the Aberdare Coal Measures, preserved as a shallow impression in grey shale from a colliery spoil tip. The small, wedge-shaped leaves radiate from a single node and show faint internal venation; preservation is fragmentary but typical of hand-collected material from shale on South Wales tips. (Leaves about 1cm across.)

Fig. 9. Paired impressions of *Sphenophyllum* leaf whorls. Two separate specimens showing the characteristic star-shaped arrangement of wedge-shaped leaves radiating from a central node. Although preserved as flattened impressions in fine mudstone, the radial symmetry and narrow, tapering leaves are diagnostic of *Sphenophyllum*. (Leaves about 1cm across.)

*What was Sphenophyllum?*
Sphenophyllum was a smaller, scrambling relative of the horsetails, forming part of the understorey of Carboniferous swamp vegetation. Its most distinctive feature is the arrangement of wedge-shaped leaves radiating from a central node to form star-like whorls. Unlike the upright Calamites, Sphenophyllum probably grew by leaning or climbing through surrounding plants, occupying damp, disturbed ground at the margins of swamps and channels.

What was Sphenophyllum?

Sphenophyllum was a smaller, scrambling relative of the horsetails, forming part of the understorey of Carboniferous swamp vegetation. Its most distinctive feature is the arrangement of wedge-shaped leaves radiating from a central node to form star-like whorls. Unlike the upright Calamites, Sphenophyllum probably grew by leaning or climbing through surrounding plants, occupying damp, disturbed ground at the margins of swamps and channels.

Fig. 10. Small sphenophyllalean stem fragment with attached leaf whorl. A small specimen (about 1.2 × 1.2 cm) showing a slender, longitudinally striated stem consistent with *Sphenophyllum*. A lateral branch terminates in a compact cluster of short, wedge-shaped leaves interpreted as a partially preserved leaf whorl.

Fig. 11. *Sphenophyllum* stem fragments. (Left) slender, jointed stem showing distinct nodes with short, wedge-shaped leaf bases radiating from the uppermost node (top of specimen), a diagnostic feature of *Sphenophyllum*. This whorled architecture distinguishes it from *Calamites* and confirms attribution to this extinct Carboniferous climbing horsetail relative. (Right) stem fragment with at the lower right, a distinct *Annularia* leaf whorl (from a *Calamites* branch) preserved on the same slab, recording the close physical association of different horsetail relatives within Carboniferous wetland vegetation, and highlighting the mixed plant debris typical of coal-measure deposits. (Each about 2.5cm long.)

(2) Seed ferns

Seed ferns are also present (see box: What were seed ferns?), although typically as small fragments rather than complete fronds. Pinnules attributable to Neuropteris (Figs. 11-13) occur both in isolation and in association with other plants, reflecting the delicate construction of these fronds and their tendency to fragment during transport and burial.

What were seed ferns?
Seed ferns were an extinct group of plants that combined fern-like foliage with seed-based reproduction. Although their leaves closely resemble those of true ferns, they were early seed plants and part of the lineage that eventually gave rise to modern gymnosperms. In Carboniferous coal-swamp forests, seed ferns such as Neuropteris formed a leafy understorey beneath taller vegetation. Their delicate fronds fragmented easily, which is why they are most often found as isolated pinnules in coal-measure deposits.

What were seed ferns?

Seed ferns were an extinct group of plants that combined fern-like foliage with seed-based reproduction. Although their leaves closely resemble those of true ferns, they were early seed plants and part of the lineage that eventually gave rise to modern gymnosperms. In Carboniferous coal-swamp forests, seed ferns such as Neuropteris formed a leafy understorey beneath taller vegetation. Their delicate fronds fragmented easily, which is why they are most often found as isolated pinnules in coal-measure deposits.

Fig. 12. Fragments of *Neuropteris* seed-fern fronds. (Left) a partial pinnule showing the characteristic rounded outline and fine, radiating venation typical of *Neuropteris*. (Right) a narrow fragment of the central leaf stalk with attached pinnule bases. Preserved only as small, inconspicuous pieces, fossils of this type are easily overlooked in spoil-tip material, yet they represent some of the most common understorey plants of the Carboniferous coal forests. (Scale in cm.)

Fig. 13. A very small pinnule fragment of a seed fern, probably *Neuropteris*, illustrating the abundance of fragmentary foliage in coal-measure spoil. Although diminutive, such pinnules are consistent with distal or juvenile frond material. (Pinnule about 1.5cm across.)

Fig. 14. Small fragment of a probable seed-fern frond, showing a broad lamina with a central midrib and gently arching secondary veins; too incomplete for confident generic assignment.(Frond about 1.5cm across.)

(3) Rooting structures and plant associations

Rooting structures add a further dimension. Subterranean axes (Fig. 15) and mixed plant assemblages (Fig. 16) show that these plants were not isolated taxa, but components of an interconnected ecosystem.

Fig. 15. Subterranean plant axes preserved as external casts from the Aberdare Coal Measures. The specimens vary in outline, but show widely spaced, elongate to weakly lozenge-shaped rootlet scars and lack the regular pattern typical of *Stigmaria*. Preserved only as casts, they are interpreted conservatively as indeterminate rooting structures, plausibly associated with seed ferns or sphenopsids present in the same assemblage. (One is about 10cm long (left), the other is about 7cm across (right).)

Fig. 16. Plant association from the Carboniferous Coal Measures showing contrasting ecological roles. A fragment of *Neuropteris* frond (lower left) is preserved alongside an articulated stem and leaf cluster of *Sphenophyllum* (centre). The association captures plants that grew together in waterlogged coal-swamp environments, combining larger seed-fern foliage forming the understorey with slender, scrambling or climbing sphenophylls that exploited surrounding vegetation for support. (The *Neuropteris* is about 2cm long, as is the *Sphenophyllumin width.)*

Reconstructing the Carboniferous landscape

Taken together, these fragments allow a partial reconstruction of the Carboniferous coal-swamp forest (Figs. 16-18).

Fig. 17. Reconstruction of a Carboniferous sphenopsid-dominated floodplain at Aberdare. Close-up view of ribbed calamitean trunks rooted in waterlogged ground, with detached and damaged *Annularia* whorls forming leaf litter across the muddy forest floor. The absence of intact crowns reflects both preservational bias and uncertainty in canopy architecture, while the abundance of fragmented foliage mirrors the transported plant debris assemblages recovered from Aberdare spoil tips. The scene emphasises decay, disturbance and sediment reworking within low-lying coal-forest environments, rather than a static or idealised woodland, and is informed directly by the associated fossil stems, leaves and roots described in this article.

These reconstructions are not decorative, but interpretive: an attempt to rebuild a living landscape from fragmentary material collected on spoil tips. They reunite stems, leaves and roots into ecological relationships – Sphenophyllum scrambling through larger vegetation, calamitean stands occupying waterlogged ground, and seed ferns forming a dense understorey.

Fig. 18. Interpretive reconstruction of *Sphenophyllum* scrambling through the lower trunk of a *Lepidodendron* in a Carboniferous coal-swamp forest, illustrating likely ecological associations rather than a free-standing growth habit. The reconstruction is intended to reunite the scattered fossil fragments into a living landscape. A lepidodendrid trunk provides structural support, while *Sphenophyllum* exploits surrounding vegetation, reflecting growth habits inferred from both fossil associations and plant morphology. Perhaps it was the fossilised stump of one such tree that shattered my grandfather’s arm.

They also provide an unexpected connection back to the industrial story. The fossilised base of a lycopod tree – preserved as a “kettle-bottom” – may have been the very type of structure that caused the roof collapse that ended my grandfather’s working life.

Fig. 19. Reconstruction of a Carboniferous coal-forest understorey showing the likely source of *Neuropteris* foliage. Medullosan seed ferns are depicted growing beneath a canopy of lepidodendroid trees, whose trunks display softened diamond-shaped leaf scars. The large, finely divided fronds of the medullosan trees shed abundant pinnules during decay, flooding and disturbance, accounting for the isolated *Neuropteris* leaflets commonly recovered from Coal Measures mudstones and spoil-tip assemblages at Aberdare.

Where we are now

Today, Aberdare presents a softened landscape in which the physical traces of mining are increasingly difficult to discern. Yet beneath this reordered surface lie the remains of both human lives and ancient forests, layered one above the other.

What survives are fragments: fossils weathering from discarded shale, a signed cartoon preserved in a family home, a miner’s lamp, and paths that no longer lead to where they once did. Each, on its own, is incomplete. Taken together, they reconstruct a place in which deep time, industry and lived experience are inseparable – a coalfield not only of extraction, but of memory.