by Clive Thomas
It was not until September 1968 that I first became acquainted with ‘The Stinky’, the name given to the Morlais Brook by past generations of children and adults who lived along its banks.
Not being a Merthyr boy I was really unaware of its existence, let alone details of its course and history. Where I lived in Troedyrhiw we had the River Taf across the fields of Bill Jones’ farm and our only brook was an old Hill’s Plymouth Collieries’ watercourse which drained numerous disused mountainside coal levels. Despite its origins, the water was clear and clean, drinkable, dammed in the summer holidays, paddled and bathed in. When bored or just at a loose end we raced empty Bondman tobacco tins along its course, running to keep up with the flow and ensure that our own particular tin wasn’t held up by a fallen branch or trapped in an inconvenient eddy. On first encounter I couldn’t imagine any of those activities taking place along ‘The Stinky’ and my initial observations confirmed that its local name was not in any way exaggerated. Indeed, the name appropriately characterised some of its more sinister and less praiseworthy qualities.
The stretch I first got to know was, what a student of physical geography would term, the stream’s ‘Old Age’, that is the portion towards the end of its life. Indeed, one might say at its very death, for union with the parent Taf was imminent and in 1968 the confluence of the two was observable, not as now concealed beneath a highway and pedestrian pathway. To the south of the stream were some of the streets and courtways of the town, many of which were derelict and already marked as candidates for slum clearance. Within two or three years these would be swept away. Rising up from its northern bank was the huge tip of waste produced over a century earlier by the Penydarren Ironworks, its industrial waste concealed for the most part by surprisingly lush vegetation. The British Tip, as it was sometimes known, took its name from the British and Foreign Bible Society, founders of the academy which graced its summit. On its plateau top was a once grand construction, a building of a century’s age but which in many respects had seen better times. Abermorlais, the school’s official name, was most appropriate, as it proclaimed its location, at the union of Taf and Nant Morlais. Unfortunately, there was to be seen no evidence in the stream here of a course well run, more confirmation of ill use, where Sixties’ waste and detritus continued to be added to over a century’s massive abuse. A sad end indeed to what no doubt had once been in pre-industrial times a clear and unspoilt mountain stream.
Perhaps though, to gain a more comprehensive appreciation of the stream’s course, it is probably better to follow the guidance of another Thomas, and “begin at the beginning”.
Nant Morlais forms from numerous small tributaries on the slopes of Twynau Gwynion and Cefnyr Ystrad on the 560 metre contour above Pantysgallog and Dowlais. In a distance of seven and a half kilometres it descends 440 metres to its confluence with the Taf. It’s not easy walking country with the gently dipping beds of Millstone grit overlying the Carboniferous Limestone. The surface is rough with ankle breaking rocks and many sink holes to topple into. Among many, but by far the largest of these is Pwll Morlais, a deep and supreme example of what happens where the underlying Limestone has been eroded and the grit collapses into the void. Depending on the season this can be a steep sided, empty peat banked hole or after heavy rain, full to overflowing with a brew of brown froth. The song of the skylark can be enjoyed here on a fine summer day but it is also a solitary place, disconcerting or eerie even, when mist or low cloud descends and the lone walker is surprised by the frantic cry of a disturbed snipe.
On a clear day the view to the south is the trough of the Taf Valley. Always viewed into the sun so never really clear, with only silhouettes, shadows and reflections to give a hint of detail. One wonders how different it would have looked when all of the works below would have been at their height?
From Pwll Morlais, the stream is called Tor-Gwyn by the Ordnance Survey, until its junction with another parallel tributary, and thereafter it becomes Nant Morlais proper. The stream’s descent is gentle to begin with over the hard resistant gritstone. It is along this stretch that there is much evidence of the importance placed on the brook as a source of water power for the rapidly growing Dowlais Works during the early part of the nineteenth century. There are still the remains of sluices and numerous places where the course has been altered, or feeders led its water off to be stored in numerous hillside reservoirs.
Where one of these diversions fed the extensive but now dry Pitwellt Pond above Pengarnddu, the Brook leaves the Millstone Grit and begins to cut a deep gorge into the softer Coal Measure rocks. From here there is more urgency in its flow, its course becomes narrower and more confined. At several locations it caused railway builders of the past to pause and consider the inconvenience of its course which would necessitate the construction of embankments and small bridges. The line which took limestone to the ironworks at Rhymney crossed hereabouts, as did the Brecon and Merthyr Railway on its way north over the Beacons and the London and North Western on its descent into Merthyr Tydfil via the ‘Miler’ or Morlais Tunnel.
More significantly however, it is within this section of the stream that geologists have been able to discover some of the secrets of the South Wales Coalfield and probably many hundreds of school pupils, university students, and local amateur geologists will have benefitted from the instruction of teachers like Ron Gethin, Tom Sharpe or John Perkins. Like myself on many occasions I am sure, they have stumbled down its steep banks into the course of the stream below Blaen Morlais Farm in search of Gastriocerassubcranatum or Gastriocerascancellatum . Not valuable minerals these, but the important fossils which would indicate the location of one or other of the marine bands which were significant in determining the sequence of sedimentation of the rocks generally, and the coal seams in particular.
To be continued…..