This shoulder of the Cheviot Hills has always been an edge-land. It marks the watershed between the Rule and the Liddel, and the frontier between Scotland and England. Leaving the road, I trudge uphill for two miles through sitka spruce and pine plantation before, with two steps, leaving the firm footing of the forestry track for the uncertain realm of sphagnum. Here the spruces give way to open hill: the ground was too high and too wet even for the zealous tree planters of the 1960s. I squelch on, the brown ooze rising halfway up my waterproof gaiters as the mat of moss and heather quakes with each stride.
On a clear day, the Borders spreads out below you from this point: the extinct volcano of Ruberslaw like a headless corpse, the three humps of the Eildon Hills, where Thomas the Rhymer is said to have slipped into the fairy world. But today I am met with nothing but a wall of swirling cloud, and a wind that snaps the hood of my anorak across my face.
With no view to admire, I look instead at my feet. There are the luminous greens and purples of sphagnum moss, the burnt brown remains of cloudberry leaves (Rubus chamaemorus), the glossy leaves of great wood-rush (Luzula sylvatica). Every so often I pass a ghostly patch of bog asphodel (Narthecium ossifragum), the dead flower spikes and leaves spread out among the heather.
I follow an old march line of fence posts to an outcrop of grey sandstone, Carlin Tooth (carlin is Scots for an old woman, or witch). From the dank underside of the crag, liverworts and ferns peer out. On the flank of the hill below is a row of plastic tree guards – native junipers (Juniperus communis); it has taken the bushy saplings more than 15 years to clear the tops of their stocky tubes.
Life on the windswept rocks moves to an even slower beat. The pitted sandstone pulses with what Elizabeth Bishop called the “still explosions” of lichen, silent detonations that may have begun when the hooves of Border reivers still thudded through the heather.