Almost at the geographic heart of the contiguous 48 states, Chase County, Kan. with its dirt roads and scattered settlements, its flash floods, tornadoes, and dust storms is still pretty much the sort of place Dorothy and Toto left to visit Oz. Its population is nearly what it was in 1873 3,013, or about ''four persons to the square mile'' and so, by and large, is its rural way of life. What makes the county unique is its prairie land, ''the last long-grass acreage of any size remaining in the country.'' And what brought William Least Heat-Moon to the Kansas prairie of PrairyErth was ''some dim urge to encounter the alien.''
But after spending the better part of 30 months ''digging, sifting, sorting'' through the county's natural and social histories, and speaking with its residents (everyone from conservationists and stonecutters to coyote hunters and ''a radicalized, storefront feminist whose job is to get cowboys to eat quiche Lorraine even if they call it quick lorn''), he found himself with plenty of good stories to tell and no clear way to structure a book. Searching after a narrative form to press his material ''into cohesion,'' he kept edging, he writes, ''toward distortion, when what I wanted was accuracy.'' His solution, finally, was to ''gather up items like creek pebbles into a bag and then let them tumble into their own pattern.''
Though Heat-Moon's ''reality of randomness'' may sound like a smooth rationalization for chaos, PrairyErth (the title comes from an archaic term for the soil of the central grasslands) miraculously holds fast. It's not the structure that's the problem, it's the size.
Nothing, it seems, that Heat-Moon saw, found, thought about, or heard in Kansas goes unrecorded. What often begins as meditative turns, all too often, either schoolteacherish (''I must for a moment speak in numbers: the average annual precipitation here is thirty-two inches'') or encyclopedic. A chapter on the native Wind People of Kansas, for instance, includes a list of all 140 variations on the tribal name, while a section about early white settlers features the complete inventory of nearly 150 household items auctioned off at an 1860 estate sale: 2 hatchets, 4 chisels, 7 augers, 4 washtubs, 1 shovel, etc.
For every stunning essay, there's another that's lifeless; for every sharply drawn character sketch, there's another that's flat; and for every beautifully written passage, there's a burst of manic prose that sounds like a bad pastiche of Allen Ginsberg (''Now, coyote: yipping, ululating, singing, freely, freely, night-flute coyote''). Again and again, Heat-Moon virtually goads you to skim, and at one point, with a touch of condescension, he even invites you to do so: ''Thoroughfare readers not happy on byways may proceed to the next chapter.''
Shortened by half, this would probably be a masterpiece. At 600-plus pages, PrairyErth is like the prairie itself: gorgeous in its details, numbing in its immensity. B