Were this dry-stone wall a compass needle, it would run south-east, north-west. As the sun gathers height in the early morning at this time of year, it creates a flank of shadow the shape of a wedge. Today, this shadow tapers to my feet, atop the wall at its northern end on the coldest morning of the cooling year. Timing and temperature need to be just right: my watch reads 2C, 9.15am. I’m watching two seasons over a boundary of light.
I love watching shadow frost melt. It’s a perfect demonstration of the powerful yet strangely delicate touch of the sun – of heat that has created this line between states, seasons, night and day, between shadow and light. And only the movement of the Earth can extend its creep, into the shadow and its dusting of pale luminance.
They are pretty, these frost pockets: winter’s first breath. But frost is a remarkable force. Hand in hand with shadow, it has the power to break mountains, to prolong glaciers that deepen valleys, to vanquish vegetation.
Here at this little wall, the effect is less dramatic, but still here. As the sun lifts, the upturned cope stones are a colonnade of little summits, like mountain faces in miniature. In the shadow on the northern side, the now withering greenery is edged with a delicate corona of ice. Balls of moss cling to the stone, each like a frozen little stud of crystals, each so tiny just the touch of a finger would melt it.
I climb over to the southern side, where the sun has warmed the pale matt to a glistening, rich green. The smell is a surprise: piquant, strong, as if unlocked by the sun. At a broken down part of the wall I find the line of light and see a frost-rimmed nettle leaf begin to catch the sun. Within minutes the crystalline white and matt green become a saturated, smeary gleam. In the distant dips of the fields, a light mist is rising as this tiny spectacle repeats, everywhere. I almost expect to hear a crackle.
