From the 31st floor of the Carlyle Hotel, Jean Marie Auel can look out this winter day into a chill, drippy mist rolling in on Manhattan like the breath of the Ice Age glaciers that haunt her mind.

Out there in the ghostly fog hover the questions that send her imagination leaping back 35,000 years to a world half-fantasy, half-real -- a world of flint-knappers and cave lions, of aurochs and mammoths, of Cro-Magnons and Neanderthals.

It may be the least probable setting for a best-selling novel since "Watership Down": a mind-teasing blend of archeology, paleontological botany, Outward Bound survivalism, geophysics and "Flame-and-the-Flower" romance.

Auel, however, has not only made it work twice ("Clan of the Cave Bear" and "Valley of the Horses"), but has rewritten publishing history her third time around. Fueled by a firestorm of advance sales, Auel's third novel, "The Mammoth Hunters," swept to an unprecedented first hard-cover printing of 1.1 million copies -- dwarfing the previous bests of such proven big-book titans as James Michener (750,000 copies for "Texas").

By the Dec. 6 publication date a staggering 1.5 million copies of the appropriately elephantine (656 pages) novel were in print. "Mammoth" had lumbered confidently to the top of the best-seller lists, where it's been ever since. Auel's other two books were booming again in paperback. A major screen production of "Cave Bear," starring Daryl Hannah of "Splash" fame, was on its way (it opens today in Washington). And Auel (pronounced "owl"), a plump, self-assured grandmother from Oregon who married young, raised five kids and never wrote a thing until she was 40, was staring out at the fog and musing on what it all means.

"You know what luxury is?" she says. "It's being able to go to sleep when you're tired and waking up when you want. Keeping your own schedule, not someone else's. It's being able to learn as much as you want about whatever you want and be paid to do it. I think I've found what I want to do when I grow up."

Seated primly, smoothing the skirt of her light gray suit, Auel sort of resembles, with her round, bespectacled face, the third-grade teacher you always liked. And like the teacher, she makes her stories parables.

"Clan of the Cave Bear" unleashed on the literary world a Cro-Magnon wonder woman named Ayla who, orphaned in an earthquake, is raised by a tribe of racially doomed Neanderthals and conditioned to their culture, only to be expelled from the tribe by a new leader hostile to her humanity.

"Valley of the Horses" details Ayla's solo evolution into a sort of Jackie of all caves and introduces her to the first non-Neanderthal male she's ever seen -- Jondalar of the Zelandoni -- with whom she discovers "the pleasures of the sleeping furs" and rides off into the paleolithic sunset.

In Auel's third book, Ayla is wooed away for a time by a dark-skinned ivory carver, and she and Jondalar agonize through fully 400 pages of missed emotional signals until the novel starts to read more like "The Heart Is a Lonely Mammoth Hunter."

But woven through all three volumes is a texture of fact and imagination that Auel confesses is "the real reward in all this": the environment and technology of ancient man.

Newsweek may call her books "late-Pleistocene Harold Robbins," but anthropologists praise them for their scientific grounding. Auel has slept in ice caves, chipped arrowheads from flint, boiled soup in pots of animal skin and grubbed for medicinal herbs on the steppes of Russia. She knows about Earth-mother totems carved in ivory and musical instruments made of mammoth bones and how to make a fire without matches -- all of it learned in a whirlwind of scholarship spawned by the midlife desire to tell a tale.

"A couple of months ago I attended a dinner at the Center for the Study of Early Man at the University of Maine," she says. "And one of the scholars there said something in a speech that meant more than anything to me. He said 'She is a true scientist.' "

Auel's journey to Ice Age celebrity is every bit as intriguing as Ayla's and no more probable. The second of five children of a Chicago house painter, she married at 18, had five children by the age of 25 and frantically juggled ironing, laundry and car pools during the day with a night job keypunching billing orders for J.C. Penney.

She might have remained just another daydreaming housewife, she says, had she not read Betty Friedan's "The Feminine Mystique," which convinced her that she could accomplish anything she put her mind to. She had graduated from Chicago's Jones Commercial High School and was now (in the mid-'60s) doing technical writing and designing circuit boards in a Portland, Ore., electronics firm where her husband worked as a corporate planner. She decided she wanted to be a physicist. She had never gone to college, so she entered night school to study mathematics, electronics, Russian and physics. "I wanted to learn how things worked," she says.

Physics, however, proved too demanding for someone combining parenting and work. She decided instead to enter a special program at the University of Portland that would permit her to win a master's degree in business administration without earning a bachelor's degree first. Her husband Ray, unenthusiastic about her first return to college, was won over by her determination. He entered the program, too. They went to night classes for 12 years.

"Getting the MBA was a big symbolic thing for me," she says. "It meant I could have my own professional career." With the degree in hand, she quit her job at the electronics firm, "but I didn't know exactly what I wanted to do." Idly, one night she sat down and started to write a story.

Although a voracious reader since childhood, "I had never really written anything other than the sort of poems and stories you do in school, but I had this vague idea about a girl in some prehistoric era raised by people very different from her. I visualized this girl living with an old man who had some sort of crippled arm."

She started writing, but quickly realized that "I didn't know anything about these people -- how they lived, what they ate, nothing." She turned to the Encyclopedia Britannica "but you know how that is, it either tells you too much about something or not enough." She moved next to the Portland Library, and soon had checked out "about 50 books -- anthropology, archeology everything about ancient man. And all this for a story I was just writing until I found the right job."

Yet it was much more than just a pastime.

"You have to understand, I was in a sort of free-floating state. From the time I was 18 I had spent almost every minute of my life raising my family, working or going to school. Now here I was, with my MBA, the kids were grown, I was 40 years old and doing something I cared about that was all mine for the first time."

One day she opened a book called "Shanidar," about the excavation of a cave in Iraq containing several Neanderthal skeletons. The excavation had revolutionized thinking about Neanderthals, long pictured as primitive, slack-jawed cousins of prehistoric man, dragging their knuckles toward an evolutionary dead end.

Microscopic analysis of pollen grains found on one skeleton in the cave indicated it had been covered with flowers and medicinal herbs: a ritual burial in a species presumed far too crude for such sensitivity.

But eerier yet was the description of the skeleton in question: It was that of an aged Neanderthal man. With a crippled arm.

"Talk about creepy! There was the old man in my story! He had really existed! I had to know more."

Veneration of such an elderly and deformed individual, anthropologists decided, meant that man's prehistoric ancestors didn't kill or drive off the weak and aged like the brutes they had always been assumed to be. Decided Auel: "They had thoughts and feelings and emotions. They were just like us."

The more she read, the more the story grew in her mind. She was obsessed. She wrote and wrote for six months, and when she finally stopped, she realized she didn't have a story any more. She had a novel in six parts.

"But it was terrible," she said. "All my feeling for these characters wasn't there. I didn't know anything about writing."

She went back to the library for books on how to write.

Meanwhile, she had answered an ad for a credit analyst in the Portland branch of a large California bank. Negotiations pushed both the salary and the responsibility of the job upward until "all of a sudden I realized this was serious. Here was a serious job, a real career, every kind of opportunity I had thought I wanted. We needed the money. We had three kids in college. Yet I was deep into writing this thing, and it wouldn't let me go. The idea of abandoning it brought tears to my eyes."

Her family was supportive but understandably cautious. "My son told me, 'Remember, Mom, a job in the bank is worth two in the book.' " Ray Auel, a trim, low-key sort with metal-rim spectacles and red hair, remembers telling his wife "I thought she could do both." Auel, however, feared that if she removed her mind and energy from Ayla and the Ice Age even temporarily to start the new job, "I'd never get her back."

It was, she says in retrospect, one of the major decisions of her life, and she told herself, "Okay, if you're giving this up you better be serious about writing." She turned down the bank, but vowed to see the book through to publication, no matter how long it took.

Diving into a rewrite of her story, she poured out 450,000 words, then realized her six-part novel was really six novels. Working through the nights, eight to 16 hours at a stretch, she rewrote "Clan of the Cave Bear" four times. After several rejections, she sent it with a 10-page bibliography to Jean Naggar, an agent she had met at a writer's conference several years before. Naggar responded with a contract and promptly sold "Cave Bear" to Crown Books for $130,000, a first-novel record at the time. Ray quit his job at the electronics firm to become his wife's business manager. Jean Auel had found her career after all.

The dimensions of Auel's success in the lawyer- and accountant-dominated world of modern publishing are not easy for the layman to grasp, but some figures from Crown Books give a rough idea.

"Clan of the Cave Bear," published in December 1980, sold 370,000 hard-cover copies in 14 printings before it invaded the paperback market. It was on the New York Times best-seller list for 18 weeks. In mass-market paperback it was on the best-seller list for 12 weeks in 1981, came back on for 9 weeks in '82, was on for 21 weeks in '83-'84 and re-emerged for 5 weeks in '85 and 6 weeks so far in '86. More than 4.2 million paperback copies have been printed.

"Valley of the Horses," with 22 hard-cover printings and 675,000 copies sold, was on the hard-cover best-seller list for 47 weeks, and as a mass-market paperback was on for 20 weeks in '82-'83, 20 more weeks in '84, 2 weeks in '85 and 7 so far in '86, with nearly 3.3 million paperback copies printed.

"Each new Auel book has meant tremendous additional sales of the others," a Crown spokesman says. "It's really rather incredible."

Only her accountant knows just how much this means to Auel, but her agent says a conservative estimate is that "we're well into the seven figures" for both "Cave Bear" and "Horses." As for "The Mammoth Hunters," Naggar says, hardback, paperback, book-club and foreign rights alone will mean a minimum of $5 million "over time" for her client. That's without figuring either movie rights or Auel's percentage of actual book sales.

Auel is candidly proud of her achievements, but a little staggered by it all. Aside from a fancy house on the Oregon coast and some research travel, she and her husband try to take things as they come. "We're very aware of the fickleness of public taste," says Ray Auel about his strategy for investing his wife's earnings. "She didn't start out writing to make money -- she was writing what she wanted to write. I want her to be able to continue to do that. It turned out a lot of other people want to read her. That could all change tomorrow."

Still, Ayla's adventures are only half over.

Though a blond tomboy herself in her Chicago girlhood, Auel grew up with an early thirst for the printed word ("I kept asking, 'When will I learn to read?' They said, 'Not until first grade.' I was in tears") and an unbounded imagination.

"I had imaginary playmates, like a lot of kids do," she remembers. "I hated to dry the dishes so I invented one named Christine to share the chore. Christine was my friend and alter ego for some time."

With Christine, she immersed herself not only in books ("the usual girl stuff -- 'Water Babies,' 'Black Beauty' -- plus Jack London adventure stories, science fiction, historical fiction") and the magic of radio in the '40s.

"On Saturday mornings there was a program called 'Let's Pretend,' based on fairy tales and other stories. That was one of my favorites. Radio fit right in with my imaginary playmates. It was all done inside your head.

"I learned a lot from radio about telling stories. It placed a heavy premium on character development and narrative. Writing is not so different in some ways. Sometimes I feel now like I'm just writing down my imaginary playmates."

Auel says she never really set out to create an alter ego in Ayla, who is not only the fastest, most accurate and quickest reloading slingshot on the steppes but an accomplished medicine woman, animal tamer, potter, basket weaver, horsewoman, trapper and flint-knapper as well. Ayla talks to the animals like an Ice Age Dolittle, domesticates the horse and dog, invents the travois, discovers how to make fire with flint, figures out conception and occasionally takes deliciously Freudian bareback rides on her pet cave lion. She also cooks gourmet ptarmigan, of course, and makes her own clothes.

"There is a campy charm to this," wrote Time magazine, "as if the author had, beyond our wildest imaginations, found a way to combine The Flintstones, Dynasty and the story of Mme. Curie."

What lifts Ayla beyond caricature is the compelling logic of her development, driven as she is to discover self-reliance in the face of alienating differences of race and culture. At their best Auel's books, particularly "Cave Bear," become novels of ideas as well as escape.

Anthropologists, for example, have puzzled for decades over why Neanderthal man died out. Auel, while generally scrupulous to the known facts about Neanderthals, decided to endow them with a dominant racial memory that wedded them to the past, while Cro-Magnon man's ability to learn and adapt better equipped him for the future.

This melding of known fact with imagination may be Auel's greatest achievement. "I don't like the seam to show," she says with a smile.

It is that integrity that scientists applaud. "On the whole, I approve very much of what she's done," says J. Lawrence Angel, senior curator of the Smithsonian's division of physical anthropology. "She has read a great deal and is extremely intelligent and sensitive. She's made a lot of people realize there is a longer history to humankind than generally thought."

"Some of what she does is fanciful, such as what these people looked like, but it's probably close to the truth," says Donald Johanson, director of the Institute of Human Origins at the University of California at Berkeley and coauthor of "Lucy: The Beginnings of Humankind." "She has done her homework in terms of what the environment was like, and she has done a great deal to bring alive all of these bones that have hung around in museums all these years."

But why did she choose the Ice Age in the first place?

"I wanted to write about how someone lives among people very different," Auel says. "I think it's a universal theme. I think even among the most loving families almost everyone goes through a stage when they feel themselves very different from the people around them."

By setting her novel far in the past, she said, "I can write about problems like racism, sexism, prejudice in such a way that people can deal with them as abstract concepts. They can have enough distance from their own lives that maybe they can think about them without the emotional hang-ups of the present day. Let's hold out something like the Neanderthals as a way of asking, 'Why can't we look at people as individuals, with individual human capacities and dignity, instead of seeing them only through group fear or prejudice?' "

Ethnocentric bias, she says, led people for years to assume that ancient man was stupid, insensitive and violent. "Yet the more we discover about them, the more we realize they had fully developed emotional lives and artistic sensibilities . . . They were very much like us. They had to be intelligent to survive.

"Think of it! An Ice Age glacier was a wall of ice two miles high!"

Being both passionate and protective toward the accuracy of her fictional world, Auel views the movie version of "Cave Bear" with obvious distress. She refuses to discuss the film but has filed a $40 million suit against the producers for what her lawyers charge are unapproved story changes, historical inaccuracies and failure to give her financial data on which to base her percentage. She is asking an additional $500,000 for delays in completion of "The Mammoth Hunters" that resulted from disputes over the film's production.

Whatever happens to the suit, Auel is due in Auckland, New Zealand, on March 1 for the start of a promotional tour of New Zealand and Australia. Her books are published in 20 countries and translated into everything from French to Serbo-Croatian. She, on the other hand, is proud of having returned the favor by financing translation of a book in Russian on Ice Age musical instruments.

She has also underwritten an upcoming symposium in Santa Fe, N.M., on the transitions between Neanderthals and early man. "The only condition I gave for the [$10,000] grant is that I get to come and listen," she says. "I owe [the scientific community] academic funding. They have given me so much."

Then it will be back to the word processor to start the fourth volume of the Earth's Children series. It's a prospect Auel views with restrained enthusiasm. Never again, she says, will she undertake to do six books on the same theme.

"I don't want to sound ungrateful to Ayla," she says. "She paid for our new house. I can afford to send my children plane tickets at Christmas. But I have a million ideas for other things I'd like to write about . . . I'm learning the difference now between obsession and discipline."