Eye on Nature: The shifting sand, shingle and stones beneath our feet

Much of the recent excess of summer was veiled on this Mayo hillside by days of Atlantic drizzle (not wholly unwelcome; we are a temperate pair). But along with media images of human throngs at the Dublin tideline came others from England that revisited my childhood: in particular, Brighton beach, packed with sun-drenched figures, the Palace Pier shimmering beyond.

I remember the same scene from August in the last few years of peacetime before the second World War, and long before the workers could afford to holiday abroad. Any glimmer of fine weather brought trainloads of “trippers” from London, marching down the hill to the sea, their shoes rippling across the grid of glass eyes in the pavement above our kitchen. By noon, down on the shingle, one had to pick one’s way between the towels.

Other images came from the beach at dusk, of couples curled up for the night, fitting hips into the warm shingle as comfortably as beanbags. I never quite managed this, even in the wilder reaches of my teens, but it brought back the salty smoothness of the pebbles, the seaweedy fragrance that clung to them, the colours and patterns revealed by a flick of the tongue.

It is hard to believe that nine-tenths of them were flint. These nodules of silica had hardened in cavities of seabed chalk, enveloping the skeletons of sponges and urchins; they were then raised up in cliffs and later scattered in chunks as these fell to the waves.

There were big knobbly flints in the wartime fields ploughed into the downs behind Brighton, and others in old, mossy walls of the town. They seemed to have little in common with the pebbles of the beach, worn down by aeons of time, the grinding of waves and storms, the long polishing of sand.

Brighton was where the Victorian craze for pebble collecting and polishing began – first, of flints sawn open to show their fossils, then of the colourful semiprecious stones that lurked among the shingle. Even my childhood lingerings, a shop near the seafront with gloriously curved windows, offered lapidary gems of onyx, jasper, agate, chalcedony, citrine, carnelian, amethyst.

None of these, by this time, came from Brighton’s shingle. (Slabs of agate were brought from Brazil.) But enough fascination remained in the shapes and colours of pebbles for trippers and their children to take pocketfuls as keepsakes.

Over the years the toll became significant, the beaches robbed of replenishment by long concrete walks hemming the bottom of the cliffs. In 2012 Brighton was asking Londoners to return their pebbles as a goodwill gesture, however quixotic this may seem.

Ireland lost nearly all its chalk in such a distant past that most of the liberated flints must now be ground into sand. Flint bands remain in the chalk cliffs of the Antrim coast, and their pebbles have drifted to beaches on both sides of the Irish Sea. On the island's southeast corner the longshore drift of stones is enriched by pebbles dropped from eroding cliffs of glacial till.

In his book for ramblers By Cliff and Shore (1992), Michael Fewer described a Co Waterford beach "made up of the most magnificently polished and rounded pebbles of quartz, jasper, sandstone, limestone and flint . . . I found it impossible to resist collecting some fine jaspers which weighed down my pockets for the rest of the day."

The grandly mixed geology of Ireland, especially at its mountainous rim, and the scouring flow of glaciers, mean that pebbles and cobbles of great beauty and variety can turn up on almost any of our shingle beaches.

A national survey in 1999 looked at 153 of them, but only for the interest of their rarer vegetation, not their stones. One of them was at Carrowniskey, just north of us, a sweeping rampart of cobbles and boulders built up by the sea.

Much of it was grey enough, heaping limestone on sandstone and granite on schist, but in my rock-hunting days I brought home a few aesthetic treasures, among them a big black egg of polished dolerite, starry with specks of quartz (I may be guessing), and curvy little pillows of conglomerate rock, studded with pebbles in pastel pink and green.

I put all that in the past because Storm Brigid, last winter, did its best to sweep the ridge away. It smothered the car park with boulders and left perhaps 10 or 12 hectares of commonage carpeted with cobbles and stones: a lunar scene. The steep, stony ridge of my drawing exists now only in memory.

It could, I suppose, rise again, as many times before – this unless the storms we are promised give it no chance to build. Meanwhile, the locals refused to give in, clearing the car park for the horse races in July along three clean kilometres of sand. And the surfers will be back in autumn, when the waves are apparently “mental but not entirely insane”.