After cutting through the steep, wooded hillsides from the much higher ground beyond, the Afon Cletwr winds inconspicuously through the village of Tre’r-ddôl. Over time, the path of this narrow river has been channelled and constrained between stone-edged banks, making it so well hidden that it is often heard before it can be seen. Passing a scattering of houses, which seem to have grown directly from the rock outcrops on which they stand, the channel broadens and empties over a stony ford towards the Afon Dyfi. Here the river loses any pretence at having a natural path, as it is caught between two wide, arrow-straight, earth banks first built in the early 1800s - part of a scheme to garner agricultural benefits from reclaiming the “wasteland” of the Cors Fochno peat bog. The air is cold and still as I stand on the grassed bund to the west of the Cletwr, but the sunlight is soft and pale, filtered through dense cloud that has robbed the day of its early promise. In the virtual silence, the staccato drumming of a woodpecker drifts across from the woods above the village. Looking towards the sea, uniform blocks of grazed pasture stand isolated by deep, steep-banked drainage rines. Lines of reeds pick out these ditches, their flags of white seed heads barely moving between the barren trees of deep winter. These linear features stand in sharp contrast to the chaotic nature of the marshland that lies between the banks of the Cletwr. In this partly tidal zone, perhaps a hundred yards across, the processes of erosion and sedimentation, plant establishment and succession, are left almost at liberty to generate the balanced organic forms of a semi-natural landscape. Further to the east, less intensively managed grassland has been invaded by soft rush, with patches of scrub and trees beyond. Apart from reed and water, the only movement is a party of rooks as they loudly dispute the occupancy of a single skeletal tree. Before the light fades further, I press on towards the main sea wall, where the embankment built for the Cambrian Railway bridges the Afon Cletwr and keeps the truly wild marshes of the Dyfi estuary at bay.