Only one other human has set foot up this Moors-edge dale since a sprinkling of snow fell, and as I ascend a lone oak-bark grey roebuck melts into the trees. I emerge on to a plateau where a band of starlings roves along a row of spindly pines which do little to curb the icy wind. Chattering goldfinches and twite racket about a cover crop gone to seed. There’s little to suggest what else is hidden here, among the dry stems, until I’m just a few paces away. If not for a rusty iron frame, I’d maybe notice nothing until an ill-fated step sent me down a brutal, near vertical 20-plus metre fall. But the chasm is marked in other ways, including a circle of green where snow has not settled, where frost has not formed. Most unsettling of all though, this ominous pit is breathing. A soft, warm, continuous animal-vegetal-mineral exhalation. The windypits of Ryedale are deeply, darkly uncanny, even before you know that some have yielded of an array of bones, including those of people, some ritually killed. The humid air smells briefly of horror – but it’s not all death down there. There’s luscious-looking hart’s tongue fern, feathery mosses, assorted grasses and herbs, and in the sultry microclimate around the edge, even freshly sprouted mushrooms. I can’t resist going again three days later, on the frozen and starry night of the new moon. It’s a fumbling walk in the dark, over frost-on-frost so thick the ground feels fuzzy. The air is so still that we climb wreathed in the fog of our own breath. The stillness and chill mean the geothermal gust is even more intense, the odour more emphatic – a scorchy mineral fug somewhere between moulder and solder, with a slight acridity that lingers at back of the throat for hours. We flick on our torches and find ourselves surrounded by a belching, reflective fog. It takes almost no imagination, now, to visualise the pit as a wyrm-hole – the lair of a coiled, somnolent dragon. We are approaching Imbolc, the pagan festival of incipient spring, when thoughts turn to rising and greening and growth. But tonight, I fancy, something else is stirring.