Point - and wait - and click

THE WOOD looks innocent – “green” in every sense of the word. The trees are in full leaf; bracken carpets the ground with a feathery freshness which suggests late spring or early summer. It’s a scene which is, to anyone who walks regularly in Ireland’s wilder places, utterly familiar.

Yet something nags at the edges of your enjoyment. A fine wire line stretching from one tree to another. A bulldozer. A pile – or is it a pyre? – of earth and wood.

What you're looking at is David Farrell's photographic series Small Acts of Memory. Since 1999 Farrell has been tracking searches for the remains of people who "disappeared" during decades of sectarian conflict in the North. His book on the subject, Innocent Landscapes, won a publishing award – but that wasn't the end of the story. Revisiting the sites several years later, Farrell realised the searches had been resumed. So he, too, resumed his patient record.

In the era of the digital image we think of photographs as instantaneous explosions of truth. Seduced by decades of high-quality photo-journalism and the buzz of instant-access global social networking, we fondly imagine that all it takes to capture the “real” story – whether it’s a street protest or a street party – is the discreet click of the mobile camera-phone. History captured in the heat of the decisive moment.

An exhibition at the Gallery of Photography invites us to re-examine that assumption. The Long Viewpresents work by six photographers who, over their careers, have adopted an approach known as "cool" or "slow" photography. The visual equivalent of slow food, it provides not just a feast for the eyes but a banquet of food for thought into the bargain. These are photographs that were made over a lengthy period of time, and which reveal themselves to the viewer gradually, even gently.An elusive, rather than a decisive moment, is how Farrell puts it. The series he calls The Swallowing Treeportrays a set of rosary beads fixed to a tree by the family of the person who is thought to be buried nearby. Since 1997, the trunk has grown around, and through, the beads.

“It’s a very powerful metaphor about a memory being swallowed by nature – which was the intention, probably, of the people who did the killing. But what struck me also was the stubborn resistance of this non-natural thing, to actually stick out and act as a reminder.”

Farrell has spent almost a decade tramping around these sites at weekends in all seasons and all weathers. Why? “Apart from the importance of the subject, and its relevance to the peace process and politics in Ireland, and commemorating the people who disappeared, it’s also about the efforts that are being made to find them,” he says. “The physical work is incredible; the dedication is quite something. I felt I was kind of honour-bound to mirror that.”

He indicates one of his larger photographs, an autumnal scene which is, at one level, a document of a hole cut through a forest.

“But it’s also a metaphor of reaching back into the past. These are the trees that grew back after the first search. So here’s a hole punched right back into the past; a hole through 10 years of history. There’s also an idea of a healing process being opened up again, like picking at a scar.”

Farrell's photographs alone would make the exhibition worthwhile. But this is a group show featuring six photographers whose work has never been exhibited together anywhere. Magnum photographer Donovan Wylie's series on abandoned British watchtowers along the Border, with their echoes of ruined castles; Paul Seawright's slices of sectarian iconography in Belfast; Anthony Haughey's studies of abandoned housing estates from the boom period, ruined castles of a different order; Richard Mosse's examination of air crashes, The Fall; Jackie Nickerson's near-miraculous portraits of everyday life in the Gulf of Arabia.

“We’re so used to photographs being used for the extraordinary,” says the exhibition’s joint curator, Trish Lambe. “And then the ordinary sails on by.”

The Long Viewis at the Gallery of Photography, Meeting House Square, Temple Bar, Dublin 2 until August 28th as part of the PhotoIreland festival