Greenwood

Waun Mawn ('peat moor') is a hill in the heart of the Preseli hills. It forms part of the watershed between the two rivers - both beautiful bodies of water - that drain the peat into the sea at Fishguard (Abergwaun) and Newport (Trefdraeth). It seems appropriate to add the Welsh names, because we are looking at deep history

On the lower southern slopes of Waun Mawn is a standing stone, along with three fallen ones. These are now believed to be the remnant of a bluestone megalithic circle that stood here 5,500 years ago, being in place for almost 400 years before, improbably, being uprooted and transported to Salisbury plain, 230 km away, to form the first stone monument - now the inner circle - at Stonehenge

We drove past today, but the stone is not visible from the road, and we were in search of a survivor of equal antiquity, just 3km away - this remnant of ancient temperate rain forest, the Tŷ Canol woodland. It grows on a shady northern slope, made steeper in places by cuttings created by streams, amidst large rock outcrops and boulder fields. Water flows into it and through it from the hill above and springs within it; the sound of runnels flowing over rock from puddle to puddle is everywhere

Unlike many such remnants, it is well-known, girded by signage, protected by many abbreviations and encircled by a national park. Many sharper eyes than mine have enumerated its many species of mosses, ferns and lichens (400 of the latter). Nevertheless it retains its ability to charm, to calm and to transport the mind to a time when men and women literally moved mountains

How do you select one picture to represent a whole wood? I toyed with one of the lovely oak-gall Mrs M found (on the 'world in a grain of sand' principle). I particularly liked one of an ancient oak forcing apart a fissure in a 3 metre high, lichen-encrusted block of stone, like Samson sundering the temple pillars. In the damp moss, an orange lichen on a log looks as if its host log is aflame

In the end, this one best conveys the gyrating, tortured, intertwined shapes formed by sessile oak branches in this harsh, wind-swept, hard-scrabble environment, where only the hard-as-nails survive. Also the ubiquitous moss, covering every surface like green snow, or the velvet on stags' new antlers, turning unyielding stone and rough bark alike to the softness of a bedtime quilt, and the epiphyte ferns on the oak branches - one of the guarantors of rainforest authenticity