COAL dug at Tan Hill warmed the garrison at Richmond Castle in the 1380s. But it was not until 1934 that Tan Hill's final shovelful was extracted. At its nineteenth century peak, the mining there took place in quite deep shafts, with winding gear and pumps powered by horses.

Beehive ovens converted much of the coal into coke, used in lead smelting, particularly at Swaledale's Old Gang mines. But the coal was so abundant that, to reach a wider market, a turnpike road was built linking Reeth with what is now the A66.

Always overshadowed by the Klondykes of lead and ironstone, the story of pre-modern coal mining in North Yorkshire makes absorbing reading in an ambitious book, Historical Atlas of North Yorkshire edited by Robin Butlin, devoted to the fledgling county. And it grabs the eye, too. For perhaps the most remarkable of the book's many pictures shows an astonishing complex of coal pits on Rudland Rigg, in the North York Moors.

Undramatic on the ground, the series of regularly spaced waste mounds, more than 600 in all, resembling punctured boils, shows up graphically in the aerial view by archaeologist Blaise Vyner. Dealing with more scattered mining in the moorland region, the accompanying text, by Robert White and John Harrison, singles out a nice detail from a report of 1791, stating that at Carr Cote, Bilsdale, "widow Holmes has given up". Today her cruck cottage is a complete ruin.

Six years in the making, and consisting of dozens of contributions by 59 experts, the book is founded on a fallacy. In his introduction, Robin Butlin, professor of historical geography at Leeds University, says that "with the creation of the county of North Yorkshire in 1974...a new geographical entity emerged." Of course it didn't. Only an administrative entity emerged.

Nor is it true, as Prof Butlin adds, that "the areas north of the Cleveland Hills...became part of Cleveland." Some escaped. But the professor's misbelief is shared by other contributors, and John Stillwell, professor of geography at Leeds University, shoots even wider of the mark. In a piece entitled Administrative Boundaries and Demographic Change, he writes: "Stockton-on-Tees, south of the River Tees, remained part of the North Riding until 1968." And in 1974, "Middlesbrough, Guisborough and Redcar were partioned off to the county of Durham." Leeds is obviously much further from Teesside and Cleveland than most of us have suspected.

Who conceived the book is unclear. But the genesis of "North Yorkshire" as the incidental outcome of changes aimed principally at uniting the conurbations of West Yorkshire, Teesside and Humberside with their social and economic hinterlands is not acknowledged. Essentially, the county is what was left after the creation of neighbouring areas. Had the Selby coalfield been developed before 1974 rather than after, that district would almost certainly have been attached to West Yorkshire or South Yorkshire, instead of stretching North Yorkshire to south of Leeds.

More important, a decision to exclude from the new book the former parts of the North Riding annexed to the now-defunct county of Cleveland denies centuries of history. It's rather perverse, for instance, to present a map of Cistercian granges omitting the Cleveland series that were part of a carefully-developed network. One wonders how the atlas would have been framed had Cleveland County embraced the Whitby district, down to Robin Hood's Bay, as originally proposed. Reasons would have been found to include it. In fact, Prof Butlin accepts a need "to stray". So Eston, whose Fountains Abbey Grange does not appear, rightly edges in with its Iron Age hillfort and nineteenth century ironstone mining. Guisborough's Tockett's Mill wins attention as "the most complete" medieval mill in "North-East Yorkshire". But its inclusion serves to highlight the absence of the perhaps more significant Guisborough Priory from a map of religious houses - though it figures on one illustrating the Dissolution.

Though models of elegance and clarity, many of the maps, the painstaking work of North York Moors cartographer Nick Staley, consist simply of symbols marking unidentified sites. Where exactly is that former deer park? Which is that country house? And could my village, or yours, be among the coloured circles and squares that pinpoint early centres of religious dissent?

For all the assembled expertise, the need to tell often big stories in small space - up to about four pages but very often less - has curtailed scope for the telling detail (like widow Holmes' unequal struggle) that brings subjects to life. For instance, Nicholas Postgate, the Catholic Martyr of the Moors, is noted without mention of the exciting discovery of his secret chapel at Egton. Speculating on the end of the Roman occupation, Peter Wilson remarks: "That there was conflict is dramatically demonstrated by the evidence of violence at Goldsborough signal station." But only a reference number directs us to a source where we could learn that the evidence included a skeleton with a dog's jaws gripping the neck.

Many other contributors were clearly working within a straitjacket. Adam Menuge, of English Heritage, observes that North Yorkshire possesses "sites pivotal in the development of garden landscape design in Britain and abroad." Yet the three arguably top examples, Castle Howard, Rievaulx Terrrace and Studley Royal, are covered in a single paragraph. And Castle Howard also receives just one sentence in an account of The Development of the Country House.

Among "gaps" admitted, but not specified, by Prof Butlin, perhaps Famous People and Literary Links will strike many readers. Fishing also seems overlooked. Even so, from geology through prehistory, the monastic era, bygone industries, including jet, alum, textiles and rabbit warrening; down byways to features like Water Races of the North York Moors and The Routeways of Medieval Ripley; then on via profiles of main towns (only Ripon in D&S Times country, Richmond a notable absentee); pausing to examine topics like The Old and New Poor Law and Political Loyalties and the Civil War; and finally considering the contemporary county, under heads such as Protected Natural Landscapes, Agriculture and Land Based Industry, and Tourism, Sport and Recreation, the Atlas covers an enormous span.

Prof Butlin is no doubt right in suggesting it will "serve to illustrate the extraordinary variety and richness of the historical heritage of North Yorkshire." It is ironic that a county without its own raison d'etre has become one of the most popular (because least spoilt) in Britain. But whether it falls prey to John Prescott's regional ambitions remains to be seen. Given the brevity of the 1974 shake-up, perhaps we should have kept the historic counties much more in the forefront of our vision.

* Historical Atlas of North Yorkshire edited by Robin Butlin (Wes-tbury Publishing, £30 hb, £20 pb)