Test strips: The Pontcysyllte Aqueduct

Words, artwork and soundscape: Rob St John The Pontcysyllte Aqueduct in North Wales carries the Llangollen Canal high above the River Dee valley. Designed by Thomas Telford and completed in 1805, the ‘Ponty’ spans over 300 metres across the wooded valley, its arches rising 38 metres through the treetops. The longest aqueduct in Great Britain,…

Words, artwork and soundscape: Rob St John

Email to someoneShare on FacebookTweet about this on Twitter

The Pontcysyllte Aqueduct in North Wales carries the Llangollen Canal high above the River Dee valley.

Designed by Thomas Telford and completed in 1805, the ‘Ponty’ spans over 300 metres across the wooded valley, its arches rising 38 metres through the treetops. The longest aqueduct in Great Britain, and the highest canal aqueduct in the world, the Pontcysyllte is both a Grade I listed building and a World Heritage Site.


Our sound walk begins at the Trevor Basin close to the northern edge of the aqueduct, where early morning walkers crunch through frozen leaves and icy puddles as a thin mist lifts into a clear blue November sky. Approaching the aqueduct, the roar of the river wells up from below, its spate a memory of storms from the week before. The canal flows steadily southward across the aqueduct’s cast iron structure, a lightbox for suspended autumn leaves in washed out yellows and oranges: oak, ash, poplar, sweet chestnut.

We follow a path down the steep valley side below the aqueduct. The trace of climbing ivy removed from the masonry pillars resembles a watershed map or root system – capillaries and tributaries moving water through the valley. Contact microphones slipped between the cracks in the stonework record the movement of the melting water moving through the aqueduct: percussive clicks and abstracted rumbles. Hydrophones record the character of moving water on the valley floor: the Dee a stream of white noise; culverted streams sounding tuned and melodic in comparison.


Back up on the aqueduct we look north-west towards Snowdonia, with the hills white with the first snows of winter, and east to the Cefn Mawr Viaduct, which carries the train line over the valley. The canal curves through a tunnel of trees south-east from the aqueduct, past a series of disused lime kilns where canal boats now moor. The line where the water laps the block work stone canal edge catches the low sun like a gleaming silver thread.

As the day progresses, the towpath becomes gradually busier with walkers, families and cyclists. The Dee valley below is a patchwork of green and white: a heat map of the sun’s arc across the morning. Robins and blue tits flit through the hedgerows, picking at hawthorn berries and rose hips. Wild clematis cascades onto the towpath like a waterfall of candyfloss. Crows bicker in neighbouring fields, dotted on telegraph wires like notes on an unruly stave.

In the dulling afternoon light we reach the Whitehouses Tunnel. Completed in 1802, and spanning 175 metres in length, it was one of the first canal tunnels in Britain constructed with a towpath. Walking through its narrow entrance, the birdsong of the surrounding landscape is quickly muted and replaced by the echoing drips of water falling from its brickwork arch. It is almost entirely dark in the middle of the tunnel, with only the half-moon patches of light at either end visible. Torchlight catches mini stalactites hanging from the ceiling and the grey, depthless flow of the water.

A horn sounds outside as a barge prepares to navigate the tunnel. As it approaches, the roar of its engine and the churning water echoes into a long, rolling drone: the tunnel acting like a giant pipe organ tuned by the movement of air and water. In this tight space, the deep sound resonates through your body. As the barge leaves, the drone fades away, and the dripping water and faint birdsong slowly return.

Field notes on recording locations
0.00–1.00
Around the Trevor Basin.
1.00–1.30
On the Pontcysyllte Aqueduct.
1.30–2.05
Water moving through the aqueduct stone and metalwork (recorded using contact microphones).
2.05–2.30
River Dee and tributaries on the valley floor (recorded using hydrophones).
2.30–3.30
Along the Llangollen Canal.
3.30–end
In the Whitehouses Tunnel.

Rob St John is an artist and writer based in Bowland, Lancashire. Focusing on the blurrings of nature and culture in contemporary landscapes, his work has been seen or heard at Tate Modern and the V+A, London, amongst many others, and in numerous artistic and academic publications.

Listen to Rob’s previous soundscapes, captured on the remote upper stretches of the Lancaster Canal and on the Leeds & Liverpool Canal

Plan your own walk along the Pontcysyllte Aqueduct.

Posted on 22/11/2019