Along the Flaggy Shore, exotic tropical corals are in bloom. You can bend down and examine their beautiful branchings and minute elaborations. For, even as the grey Atlantic swells, and a soft summer rain adds texture to the humid breeze, you are standing on an ancient African seabed.

Some 350 million years ago, before the continents were formed, this limestone pavement was a muddy ooze somewhere south of the Equator. The vividly white coral fossils that are etched with such delicacy on to the surface of the grey stone that runs all along this magical stretch of shore on the south side of Galway Bay speak of other places, warmer climes, incomprehensibly distant aeons.

This is a place of alluring anomalies, where sea and land refuse to be neatly divided. They melt into a literal grey area – grey sky, grey water, grey rock – where nothing is black and white and everything is suspended between opposites.

To amble along the Flaggy Shore, between New Quay and Finavarra Point on the northernmost edge of Co Clare is a short walk in space but a long one in time. Doubly so, indeed: when you turn off the main road and head down towards the nearby coast, you enter geological time, moving into a space that is obviously shaped by a chronology that belongs, not to us, but to the earth.

And this walk is not to be done briskly. If you wanted to, you could do it there and back in an hour. But the point of the place is its density. Physically and imaginatively, it is clotted with tiny wonders that demand attention.

From the Ó Dálaighs to Heaney
It is doubtful that any short stretch of the Irish coast is so rich in literary associations. At one end, Finavarra, is the site of the 15th-century bardic school of the Ó Dálaigh poets. At the other, where the walk begins, is the little pier below Linnane's wonderful seafood bar. The fourth part of Bernard Shaw's epic play Back to Methuselah begins in 3000 BC "on Burrin pier, on the south shore of Galway bay in Ireland" – exactly on this spot: Shaw wrote it in a hut beside the pier, and the Flaggy Shore evidently got him thinking in slow time too. (New Quay was – and sometimes still is – called Burrin or Burren.)

Shaw was here because he was staying in Augusta Gregory's summer house, Mount Vernon, still standing at the eastern end of the shore, with its clean white walls and red-framed windows and the three cypress trees that are said to have been a gift from George Washington to his friend (and Gregory's ancestor) William Persse.

Augustus John stayed here (and designed the fireplaces). The shore did strange things to the arch-realist George Moore, who claimed to have actually seen the emanation of the spirit of Cathleen Ní Houlihan here.

William Butler Yeats wrote The Player Queen and The Dreaming of the Bones looking out over these waves and rocks. In the latter, the young fugitive says he is to wait until a currach from the Aran islands puts in "At Muckanish or at the rocky shore/ Under Finvara, but would break my neck/ If I went stumbling there alone in the dark."

In one of his finest poems, Postscript, Seamus Heaney urges: "And some time make the time to drive out west / Into County Clare, along the Flaggy Shore / In September or October, when the wind / And the light are working off each other . . . "

These imaginative associations thicken the place, but this landscape has its own natural poetry too. It asks to be watched closely, and one of its keenest observers is Gordon D’Arcy, environmentalist, teacher and painter, especially, of birds.

As we walk the shore, he reads it for me. He points across at the low hill that forms the far side of the inlet: “That’s a drowned drumlin. Twelve-thousand years ago the sea level was 300ft lower, so this would have been a great prairie like the Serengeti. You can imagine wolves standing on top of the hill looking down on the herds of reindeer roaming across what is now the bay.”

The sea was land and the land we are walking on – the flat limestone pavement – was once a seabed. The workings of huge natural forces are written on its surface, not just the dappled coral fossils but the straight tramlines that seen to have been recently scratched by some machine.

“Those,” says D’Arcy, “are glacial striae, cut by the movement of the ice at the end of the Ice Age. You see that they move from northeast to southwest in the direction of the retreating glaciers.”

But the great Burren anomaly – the flowering rocks – operates even on this exposed carpet of stones. Lichen colour the rocks in fixed patterns – black at the water’s edge, then yellow, then white. D’Arcy names the plants that proliferate along the way: campion, sea radish, sea blight, scurvy grass, sea lettuce, mayweed.

We stop to pick some rock samphire, the green stalky plant that King Lear sees being gathered on the English coast. At his urging, I taste it sceptically: it is crisp and salty as a cashew.

We divert into a field that runs between the shore and a low hill that is marked by the Burren’s distinctive seven rings of stone.

D’Arcy wants to show me a huge erratic boulder, two tons of shiny granite, alien to this limestone territory but carried all the way here from Connemara and deposited by the shifting ice. Delightfully, it has its own miniature ecosystem – the hairy green lichen that grows on its leeward side, out of the wind, is a resident alien. It will not grow on the acidic limestone that is all around but is at home on its own refugee rock.

The ordinary made meaningful
Even the ordinary here turns out to be meaningful. I remark on the profusion of yellow ragwort on the fringes of the field. Is it not a poisonous menace? D'Arcy will have none of it. "The ragwort is vital for the lovely, black and red, delta-shaped cinnabar moth, which lays its eggs on the underside of the leaves." And indeed, a short search comes up with a cinnabar caterpillar, clinging lazily to a ragwort stalk.

Birds populate the air. A majestic gannet spirals and loops just beyond the shore, its eyes beamed for the silver glint of mackerel. A black-headed stonechat flits among the grasses, then stops on a flagstone to feed its young. Sparrowhawks raise small birds in startled clouds.

The curlews call from the spray-wet rocks, and I think again of Yeats hearing that same sound in this same place: “My heart ran wild when it heard / The curlew cry before dawn”.

In May, the Flaggy Shore is mobbed by the curlew’s smaller cousins, the whimbrels, which rest here on their epic journey from Africa to the Arctic. We don’t expect to see them in August, but we are rewarded with the sound of their distinctive seven-note whistle and see a pair heading back south.

But D'Arcy is determined to hunt for the most anomalous of creatures, one that is found in Ireland only here. The land winkle, which lives up to its proper name of pomatias elegans, is a natural oddity, a sea snail that has evolved to live on the land.

After carefully overturning many shards of the loose limestone that gives it shelter, D’Arcy finds the little animal. Its shell has a luminescent pinkish glow that is indeed elegant, and it twists round in a manner that reminds me of the top of an ice cream but that D’Arcy, more romantically, describes as being “like the minaret of a mosque”.

It seems – this thing of saltwater that inhabits dry land – to embody the strange beauty of the Flaggy Shore, where earth and sea refuse to hold their places, where rock itself forms, as Augustus John so beautifully put it, “an immobilised rough sea”.

We walk on to the last anomaly: a small freshwater lake, Loch Murree, which sits just yards from the shore, with no river to form an inlet and no outlet to the sea. It is bedecked by swans, perhaps the descendants of the ones Seamus Heaney saw here when they struck him, against the slate-grey surface of the lake, as being like “earthed lightning”.

Heaney celebrated the power of this shore to "catch the heart off guard and blow it open". Some places indeed blow the mind – this one blows the heart.


The Flaggy Shore: a landscape in limestone
The north Clare landscape takes in the Burren, including the Cliffs of Moher, and the Gort-Kinvarra lowlands to the west. The landscape is made up of several rock types, including the distinctive limestone of the Burren, as well as sandstone and shale.

The area is bordered by the Atlantic Ocean to the west and Galway Bay to the north, and includes the towns of Corofin, Kilfenora, Lisdoonvarna, and Doolin on the coast.

The Flaggy Shore, celebrated in a poem of the same name by Seamus Heaney, sits between the towns of Ballyvaughan (above) and Kinvara, and is just short of three kilometres. It is one of the most northerly parts of the county, and is marked by grey limestone rocks and evidence of past glacial impact on the landscape.

Lough Murree is a freshwater lake on the southern side of Galway Bay, just under five kilometres northeast of Ballyvaughan.

New Quay got its name after a new structure was built there in 1837, and Aughinish Island lies across the channel. Structures of historical significance in the area include two Martello towers at Finavarra Point and on Aughinish Island.

Attractions and activities
You don't have to have deep pockets to enjoy the Flaggy Shore. Simple pleasures include safe sandy beaches, rock pools near the shore, and scenic, not-very-taxing nature strolls.

For the more adventurous, the North Clare Sea Kayaking Company (northclareseakayaking.com) offers tours of the coastline near Flaggy Shore and the wider area. The experienced team operates from Doolin.

The Russell Gallery (russellgallery.net) in New Quay is in a lovely 18th-century building, and displays the works of up to 20 Irish artists.

Walking is a well-developed industry in the north Clare region. Tony Kirby’s Burren walk from Kilnaboy is a popular choice. Other options include Burren Hill Walks, from Ballyvaughan, while Flaggy Shore walk is an easy, scenic loop of about three miles, beginning at Linnane’s Bar.

Mount Vernon country house B&B (below, mountvernon.ie), set in a stunning location with an old-world feel, is the former summer house of Lady Gregory, and it’s worth paying slightly extra for the sea views.

Dining options include Linnane’s Lobster Bar, which often requires advance booking on weekends. Down the road, Monk’s Bar & Restaurant is famed for its seafood chowder.