Picasso hated Pierre Bonnard's work and was oblivious to its appeal, dismissing it as "a pot pourri of indecision". You can see what he meant. In contrast to Picasso's gestural decisiveness, Bonnard's paintings are painstakingly built up through the accumulation of myriad tiny brush-strokes, pot pourris of different colours that miraculously combine to produce radiant, beautifully textured images.

The chances are that Picasso wouldn't have been any more favourably inclined towards David Crone's paintings, currently the subject of a major retrospective exhibition at the Ulster Museum. There is a curious affinity between his work and Bonnard's, and you can easily get lost in the densely patterned, thickly textured surfaces that he creates.

In fact, being lost is a state that Crone seems to actively encourage. "The best paintings come about when you are not aware of where you are, or how you feel," he has said. And looking at his work in the Ulster Museum, you get the feeling that he is happiest himself when adrift in the strangely non-specific world of his work, immersed in paintings that delight in their own ambiguity of depth and form.

Though he was never an abstract painter, some of his pictures can appear abstract at first glance because of the way representational content is so comprehensively embedded in their fabric, like fossils in limestone. In his foreword to the exhibition catalogue, Michael Longley writes of how the layering implicit in each final image reflects the geological, topographical and cultural layering that informs Crone's sensibility.

He knows this because, he notes, there is a certain level of shared experience. Like him, Crone was born in Belfast and lived on the Lisburn Road, and they have in common memories of the city in their youth, of "a terrain where the urban and the rural impinged on each other with an incongruity so intense it obliterated comfortable concepts of the suburban". That sense of indeterminate, overlapping terrains is central to Crone's paintings. They reflect, though, not static memories of a fixed past - he has several times expressed his distaste of the sentiment that such a notion implies - but the refusal of the past to stay fixed.

He is a painter of place, a Belfast painter, without any of the tweeness or nostalgia that such a statement might imply, and throughout his career he has charted the continual and radical changes in the city's physical and psychological environment in his own lifetime. In conversation, and without referring at all to his own work, he alluded to the disorientating experience of moving through a building that he knew as a child but which now has a different role entirely. He can still see and feel the ghostly traces of its past function and atmosphere overlaid on its re-invented present. That exact phenomenon is integral to the layering Longley speaks of, and informs the work's strange multi-dimensionality.

Crone's father was an engine driver with the Great Northern Railway. He went to Annadale Grammar School where he was lucky enough to encounter enthusiastic art teachers, unusual enough at the time. He enrolled in the Belfast College of Art in 1956, to study not painting but sculpture, because, as he recalls it now, he rather dutifully felt that sculpture seemed like an appropriate use of his abilities. Yet by the time he finished at college he had begun to think in terms of painting - and was encouraged in that direction by Tom Carr.

The ethos in the college was, not surprisingly, aesthetically conservative. Against this background, visits to London were a revelation. "We simply had no idea what was going on." In particular, the impact of the scale and scope of American painting, reflected in some of the art being made in Britain, was unprecedented.

The Abstract Expressionists were important exemplars, particularly de Kooning, though there are also parallels between the later, figurative work of Philip Guston and Crone's approach to figuration. Bonnard, obviously, and Georges Braque are other significant reference points, but influence often works in mysterious ways, and specific instances can be hard to pin down. Still, an empathy with all of these artists is certainly evident in Crone's work.

He has taught more or less since finishing college, and he is an enthusiastic teacher, though not particularly enamoured of administration. Contact with students is what sparks his interest. He has learned to accommodate the rhythms of teaching into his work, believing that the appearance of his paintings is partly due to constant interruptions in their making.

The gradual, incremental approach suits him: "Because I keep coming back to it, I don't have a consistent view of a piece." However, until he started teaching at third level in 1975, he was a full-time second-level art teacher, mostly at his old school, Annadale, and that was more difficult to reconcile with his own painting.

For Crone the city is always a place of deceptive surfaces. His views of shop windows, metaphors of city life, present us with bewildering composites. We simultaneously see the window, the shop interior and the reflected street, not to mention the possible reflections of reflections. Everything - people, furniture, buildings - is captured at odd, disconcerting angles. Inhabiting this confused hall of mirrors are individuals who project themselves and are perceived in different ways and on different levels.

All the time in the city, he observes, we glimpse, and are struck by, people absorbed in their own lives, stories that we will never hear. We also continually encounter a different kind of opacity, in the form of people who are defined by their role: the shop assistant, the bus driver.

Then there are aspirational images contained in clothes, accessories and other goods. Racks of clothes become roles that we would like to, or perhaps have to play. Two Mannequins Becoming Myth (1988), is about the idea of the shop window display as a mythic, aspirational image for our time.

This urban multiplicity continued, in a surreal way, throughout the Troubles. Victim, Tourist and Model (1990) is an important picture, a portrait of Belfast during the Troubles, a painting about the incongruous juxtaposition of different levels of simultaneous experience.

That is, your experience of the city depends on your role, which is a compound of choice, chance and circumstance. But no level is untouched by the underlying crisis, no matter how distant it seems, hence the air of suppressed hysteria, the pressure-cooker atmosphere.

Throughout this time, Crone and his family (his wife Deirdre is an illustrator with the Ulster Museum, and they have two children, now grown up) lived in Holywood, but in 1994 they moved to a timber-framed house on about two acres in the country, close to a small village, The Spa, south of Belfast. Though they'd always lived in an urban environment, moving to the country had been a long-term aim, and the rural setting gradually found its way into his work.

As we might expect, however, in the light of Longley's observation about the mingling of urban and rural, Crone does not view the countryside in terms of pastoral idyll. Field (1996), with its rippling, horizontal accents, suggests that the landscape is as densely layered, physically and psychologically, as the cityscape. Pool, from the same year, is a rural counterpart of the shop windows, with the disorientating transparency of its interlocking planes.

Yet there is arguably a greater mellowness to the work since the move to the country. Another 1996 painting, Garden is aglow with luminous yellows, and its spaces are noticeably less congested than usual.

Previously Crone has consciously cleared the decks in a comparable way. Thinking Space from 1990, with its calm, neutral expanses, is an unusually explicit acknowledgement of how he internalises his subject matter, so that his paintings are like maps of his imagination. His paintings are literally, for us as for him, thinking spaces, and the indications are that the move away from the city has provided more space in every sense. This hugely enjoyable exhibition confirms his status as one of the most consistently interesting artists in Ireland.

David Crone: Paintings 19631999, is at the Ulster Museum, Belfast until March 5th. An illustrated catalogue, with texts by Michael Longley, S.B. Kennedy and Slavka Sverakova is available for £9.95 sterling paperback and £24.95 sterling hardback