The railway line runs parallel to the river.

Alston, Cumbria: The path follows a long-closed branch lineandpasses through a valley layered with history

The shadow of a semaphore signal falls diagonally across the tracks as we leave Alston station to head north on the South Tyne trail.Running parallel to the river, this footpath follows the restored part of a branch line that connected the high north Pennine market town with larger Haltwhistle between 1852 and its closure in 1976. Two pipers played a lament as the final train left the station. The South Tynedale Railway Preservation Society eventually aims to extend the present five-mile stretch to Haltwhistle once more.

On this sunny out-of-season Sunday, an open-sided carriage rests outside the closed train sheds. Light bounces off the river to flicker across line-side silver birches. The level path makes for fast walking as we meet dog walkers, families and runners. Where a bridge spans the river, polypody ferns have gained a toehold in the spongy mosses that cling to stonework.

We pass thickets of spiny sloe bushes, picked bare of their fruits. The railway banks are a winter tangle of dried stems: meadowsweet, burdock, knapweed, wild raspberry and the curled seedheads of rosebay willowherb. Across the river, set in stone-walled fields, stands Randalholme Hall, a 14th-century tower house.

This is a walk through multilayered history in a valley that has long been exploited for its minerals. Scattered over the map are numerous references to shafts, quarries, workings and levels. Above us to the west is the Roman fort of Epiacum, which archaeologists believe was built to control mining for lead and silver. Later, the land produced zinc, fluorspar and coal, the railway being used for transport.

As we reach Kirkhaugh Halt with its little wooden shelter, a kestrel lifts off to stand watchful on a telegraph pole. Here, the path intersects with the 37-mile Isaac’s Tea Trail, and on the western hillside runs the Pennine Way, both more recent marks on the map’s strata. We stand on the steeply curved bridge to look up and down the line. To north is the only rock whitebeam tree in Northumberland, the nationally scarce Sorbus rupicola. Two buzzards rise up, circling in the cold air above a plundered landscape now greened by grass and copses.