And the rest, as they say, is geography

The very title, Death by Geography, has a particular resonance in the most isolated of the 26 counties. Donegal, logically and in many respects practically aligned with its immediate neighbours to the east, is only tenuously linked to the south, and has suffered economically because of its geographical position. It could also be argued that the title relates to the fact that the county's imposing physical geography sets its own limits on economic potential. As a local, the show's curator, John Cunningham from Ardara, is well qualified to broach these issues.

In fact he prefers to leave the implications of the title hanging. He does not lay out and illustrate a thesis, and indeed doesn't concern himself exclusively with Donegal. Instead, you might say that he sets out to ask some questions, open up some lines of thought, invite rather than limit speculation. The work he has chosen, ranging from Osborne to Christo, demonstrates that he is interested in the politics of geography, but also in more general perceptions of place and space, of urban as opposed to rural, for example, or real as opposed to virtual.

Even if it does nothing else (though it does), his show demonstrates the extraordinary riches now accessible in national collections. Working on the basis of an Arts Council curator's bursary award, he has been able to draw on several IMMA collections, from the OPW and Arts Council collections, and from Duchas - the latter is a really excellent little landscape by Derek Hill of Gartan, just up the road from Letterkenny.

But it is to Cunningham's credit that he hasn't just cherry-picked ready-made collections. He has also drafted in some useful reinforcements, including Limerick-based painter Bob Baker and Dutch photographer Jan Voster, who has worked extensively in Donegal. The inclusion of Baker is typical of his oblique approach to any thematic suggestion lurking in the show's title. Baker's paintings are about the shimmering, depthless surface of the television screen or computer monitor, about the substitution of the limitless possibilities of electronic simulation for the given, intractable, concrete reality of the physical environment. This is as pertinent to Donegal as anywhere - perhaps more so because there the conflicting pull of suburban and rural worlds is particularly, sometimes glaringly apparent and, for many, suburbanisation is a kind of tacit, underlying ideal, an aspiration that hasn't yet disappointed or revealed its hollowness.

You could say that Hill's Donegal, in seeming to imply an intact rural culture as well as an intact rural environment, is filtered through nostalgia, in much the same way as we now view Walter Osborne's sturdy Plough Horses - though not, funnily enough, Pieter Breughel's worldly peasants, also included in the show - but Hill's vision too is true, or at least true as an aspiration, a way of looking at things as they tenuously are and should be.

Landscape has a history, and Voster, who first visited Donegal in 1986, found himself irresistibly drawn to record traces of that history written on the land. The paradox of his topographical photographs is that the more neutral and precise they are, the greater their slow-burning emotional impact, as the photographer's meticulous attention to texture and detail allows the subject to shine with an enhanced clarity. His image of Brockagh's derelict National School might well draw us empathetically into memories of our own childhood experiences, but it also remarks on a pattern of rural depopulation.

Maria Simonds-Gooding's spare, plaster-relief painting also records the marks of human habitation inscribed on the land, with a sense of ancient, durable presence. The question of just whose land it is becomes relevant in Jonathan Ollay's startling photograph of Sangar RUC Station, a bristling, nightmarish, defensive structure, like something from a sci-fi film inserted into a rural small town. Perhaps, in a more indirect way, the same could be said of T.P. Flanagan's view of trees: it seems innocuous enough, but the criss-crossing strands of barbed wire subtly undercut the rural idyll. (I think it was Flanagan, a canny picture-maker, who once remarked that a small roll of barbed wire was a handy prop to keep in the car boot when you were out painting landscape).

If George Campbell moves towards abstracting formal patterns from landscape, Felim Egan takes the process a stage further with Downflow, a beautifully meditative composition in sand-textured greys which, Cunningham notes, was inspired by the beach at Carrickfin as the tide ebbed at dusk. It is worth pointing out this immediate link to place and time in relation to a work that adopts quite a severe, minimal language and might otherwise be taken as being entirely self-referential.

Likewise Brian O'Doherty's coloured grid, part of a substantial body of work which turns out to be quite specifically based on the Celtic linear alphabet, ogham. The Celtic romanticism of Patrick Collins's Atlantic Window, perhaps a variation on his recurrent preoccupation with Hy Brazil, is down-played by the admirable matter-of-factness of his painterly style, and what might be seen as escapist is also strictly factual: it could be Roaninish, for example, shimmering on a screen of another kind: the Atlantic haze framed by the window.

Elsewhere, the relationship of work to nominal theme is harder to discern, though there is usually an engagement with some conception of space or place. Ad Reinhardt's impassive black square screenprint, a minimal, concentrated black, is a nowhere space, but it could be infinitely deep, as opposed to Baker's electronic flicker. Michael Coleman seems to hold a spatial fabric together with bands of thread in his Divides. In Paul Mosse's mixed-media relief, masses of panel pins stand in for huge forests in a work that recalls false-colour aerial views of vast territorial expanses. At the other extreme, Fionnuala Ni Chiosain reworks the microscopic pattern of cellular structure in a plant on a hugely enlarged scale. Christo, as usual, seeks to redefine the familiar by wrapping it up.

Cunningham has selected a show that looks very good - working in association with Shaun Hannigan of Letterkenny Arts Centre - and is never overbalanced by the surprises he incorporates along the way. He does leave tantalisingly open the possibility of another, overlapping project: a view of the county in terms of the art made in or in relation to it, not as an exercise in navel gazing but as a perspective on rural Ireland in transition. In the meantime, we can eagerly anticipate the second phase of this current project, scheduled for the Letterkenny Arts Centre in October.

Death by Geography, a group exhibition curated by John M Cunningham is at Letterkenny Arts Centre, Co Donegal, until May 19th. Tel: 074-29186