Walking and Marking begins at the beginning, with A Line Made By Walking, a piece made in 1967. The line in question is of trampled grass. This simple gesture might not have the capacity to shock that it must have had at the tail end of the 60s, but it remains hugely eloquent, and, in a sense, serves to en­cap­su­late Long’s practice - in the imprint left by one short walk, he makes the natural world both his subject and his material, questions the nature of sculpture, pits absence against presence and, as the line stretches off towards the horizon, claims the act of walking, of movement in a landscape as his medium.

And, since 1967, Long hasn’t stopped walking, devising different means to record his movements.

The most striking works build on that first line by leaving marks, quiet monuments to a departed presence. A Circle In Ireland shows a ring of rocks arranged on jagged ground, Manang Circle situates another circle or stones, this time in Nepal, over­look­ing a set­tle­ment. A diptych, Stones On Stones, shows evidence of Long adding stones to the tops of cairns in Norway. Stone Line, meanwhile, brings the landscape into the gallery, with thick, irregular fingers of stone forced into unnatural linear reg­u­lar­ity.

As well as re­ar­ran­ging and tran­s­port­ing natural elements, Long uses them to create. A series of River Avon Mud Drawings are made by dipping paper in mud from the river near his home, another de­cept­ively simple act that offers breath­tak­ing results - each drawing bears evidence of mi­cro­s­cop­ic tidal patterns, that together suggest aerial views an im­pos­s­ibly dense, vast delta.

There are, too, more amorphous works, offering tan­gen­ti­al evidence of Long’s walking, con­s­ist­ing of wall texts or annotated maps. And, once again, these short state­ments are richly layered. When Long tells us that he has been ‘marking time with muddy foot­prints’ he evokes movement, landscape, and his temporary, im­per­man­ent place in it. Tide Walk is described as ‘a walk of two and a half tides relative to the walker’, a factual statement that non­eth­e­less turns con­ven­tion­al methods of marking out both time and space upside down.

When it comes to these act­iv­it­ies - words like ‘action’ or ‘per­for­m­ance’ are, perhaps, too loaded - Long also raises a thorny question: is the work to be found with Long, as he walks, or in the pho­to­graphs and text mounted in a gallery that document those works? In his essay ‘Notes on Works’, Long iden­ti­fies his texts as ‘a de­scrip­tion, or story, of a work in the landscape’ but these brief state­ments seem to be much more than a record. Like arch-con­cep­tu­al­ist Lawrence Weiner, who boiled away the physical man­i­fest­a­tions of his sculp­tures, present­ing them instead as gnomic state­ments of intent, there is a sense that when Long tells us, sometimes in the present tense, about a journey he is not only re­coun­t­ing an event from his past, but also offering the pos­s­ib­il­ity that we too might make such a journey, or even, more simply, that such journeys are possible.

It is this open-ended po­ten­ti­al­ity found in the text and pho­to­graphs that marks out Long’s best work from the weaker, often more con­ven­tion­ally sculp­tur­al pieces on show. For an untitled work from 2004, Long has marked a section of a tree trunk with fin­ger­prints of china clay, and there is a series of pieces in which similar marks are applied to Berber tent-pegs, or a found disc of scrap metal. The paintings made by casting diluted mud from the Firth of Forth onto the walls of the gallery show this divide, too. The great un­con­trolled geysers of Throwing Muddy Water contrast with the hand-made sworls and defined shape of Firth Of Forth Mud Arc, and the latter seems lacking in com­par­is­on. Long is also sometimes guilty of offering too much in­form­a­tion, as in Silbury Hill, which shows a spiral sculpture the same length as a walk down the hill in a straight line, but muddies the waters of this tran­s­form­a­tion of one structure into another by repeating a legend attached to Silbury.

In other words, when it comes to Long’s presence in his work, he either passes through it, as he passes through the landscape in its making, or stands stock still, asserting himself. And, the more evidence there is of the artist in the work, the less impact it has.

These lesser works don’t mar this ret­ro­spect­ive survey of Long’s in­flu­en­ti­al practice, though. In fact, their com­par­at­ive weakness only strengthens the best pieces found beside them, adding up to a truly re­mark­able ex­hib­i­tion, one that has the capacity to change the way we un­der­stand the en­vir­on­ment around us, and, too, the way we un­der­stand art itself.

This review was first published in The Herald on July 6th, 2007.