When our family moved from Lanarkshire to Hertfordshire, Faither promised us a penny a bucket to clear his rosebed of stones, without appreciating that we had settled on the edge of an ice sheet that had deposited gazillions of tonnes of tumbled shingle, borne south from all points north. In a single morning, we filled so many pails and plant pots that he immediately withdrew the offer, though I think he did stump up. I hold that memory in my hand and heart as I explore our new garden in Somerset. It too is littered with geological debris, though this is on a different scale to the pebbles of my childhood. Here, among the dwellings on the south side of a combe, are daily reminders of a thin and barely held division between bedrock and soil. I am still within that time of wonderment while I patrol my new domain, picking up the pieces and feeling them in my fingers, rubbing the graininess that instinct tells me should crumble but practice demonstrates has total resistance to abrasion. If my spade were to hit one of these, I daresay the spade would come off worse and I would feel the judder in my shoulder as my dad did a generation ago. These limestone chunks pave the side passage in slices the size of dinner plates, mark a border with next door’s lawn in immovable slabs, shore up the base of the rotary washing line and pepper spaces between lavender and lavatera. Their colour is variable, between light grey and burnt honey. Some are studded with fossils of marine seashells. What prompted an unknown neologist to coin a name of poetic beauty for the rock that underlies and extrudes from our surface soil? Someone dubbed this Cotswolds outlier “forest marble”, and every farm wall, barn and building of any age around here is made from it. Soft sands of ancient sea shallows, pressed, compacted and hardened over hundreds of millions of years. The rock was hewn from the land, and shaped to form the very fabric of my new home town. Country diary is on Twitter/X at @gdncountrydiary Under the Changing Skies: The Best of the Guardian’s Country Diary, 2018-2024 (Guardian Faber) is published on 26 September; pre-order now at the guardianbookshop.com and get a 20% discount