THE PLAINS OF PASSAGE By Jean M. Auel Crown. 760 pp. $24.95

THIS IS AN awful book: repetitious, ponderous, diabolically inept. Which is too bad, because there are many things in it to like, chief among them the central character, Ayla, in this fourth novel of her adventures. This book takes her and her mate, Jondalar, to his home, which he left five long wandering years before. It is an arduous trip, full of dangers from both natural phenomena -- there is a desperate, storm-drenched scramble to escape an avalanche, and a fall into a glacial crevasse -- and human treachery, the latter providing the opportunity for two terrific, hair's-breadth rescues.

Ayla is the prototypical strong female character who follows her own fate. On the way she makes an astonishing number of species-altering discoveries, such as the domestication of animals; between her ingenuity and that of Jondalar, who first appeared in the second volume, I fully expect that by the end of the series they will have health insurance and color television. One of the best things about these books is that Jean Auel presents Jondalar straightforwardly as a strong, capable man, particularly clever with tools and tool-making, and yet permits Ayla to remain the hero(ine).

But it's not enough. The writing buries it. My perception is that this one is significantly worse than the first, The Clan of the Cave Bear, which is the only other book in the series that I've read all the way through. But a lot of readers don't care how thunderingly bad the writing is; the third volume, The Mammoth Hunters, set a record as the first hardcover novel to have a first printing of more than 1 million copies.

Part of the problem is the sheer amount of description; Ayla and Jondalar often stand around telling each other things they don't need to discuss, so that Auel can clue the reader in. And there are Auel's pet subjects: When we hear about Jondalar's eyes, as we constantly do, they are "his brilliant, vivid, unbelievable blue eyes," "his amazingly vivid blue eyes," his eyes "which are such an impossibly rich shade of blue." The sex scenes, which are frequent, interminable, and embarrassing, inevitably produce such locutions as " 'I want you, Ayla,' he said, his voice suddenly ragged with feeling" (elsewhere his voice is 'husky with need'); and every "place he touched or kissed burned its way through her to the ultimate spot deep within that tingled with fire and yearning." SINCE THERE is no character development, things like the blunt repetition of Jondalar's preoccupation with whether or not "his essence or spirit {is} potent enough to start a baby growing inside a woman" are merely maddening. Because there is no sensitivity to the complexity of real people, the brisk, minute-manager way with which the severely wounded tribe (both psychically and physically) just rescued by our dauntless pair from the leadership of a madwoman is set right is horrifying. And, since this book is being read in this sick and weary world of ours, culpably irresponsible.

When Auel's details are part of the story and not shoehorned in, they are intriguing: lining the bowl of your tallow candle with lichen, for example, to make the light burn more steadily. I also appreciate a writer who includes those necessary but indelicate details of how people live, like where the latrines are and how they are maintained. But the writing can be so inconsistent and anachronistic I do not trust the reliability of her much-touted research ("her books are required reading in many anthropology courses here and in Europe," according to a publicity release from her publisher).

For example: It is drummed into us that Ayla was brought up to believe that a menstruating woman must never look a man directly in the face. Although Jondalar does not share this taboo, she is "careful not to look at him." But she hadn't been careful a few pages before -- after we'd heard about her starting her "moon time" -- and "looked up at" Jondalar, at his "expressive blue eyes," to be exact. The relationship between the two people and their horses and wolf-cub is boggy with 20th-century training language and cliches (including a few bad ones) and oh-gosh discoveries of the personalities and abilities of animals, some of it so awkward it is impossible to tell whether Auel knows which end is up on a horse or a dog -- or on human history.

It's not that there isn't a story here; it's not that the world couldn't use a good rip-snorting adventure epic about early humankind, full of fascinating prehistoric tidbits, and a few thoughts for our later time tucked among the paragraphs. But hasn't anyone heard of editing? Apparently the sales figures are all that matter, and I for one am sorry for it. Robin McKinley, author of "The Outlaws of Sherwood," is at work on her fifth novel.