The Far North of the imagination is a cartography of cartoon proportions, made even more so by the sudden celebrity of Sarah Palin. In shorthand, Alaska is white, cold and exotic, or it’s a cruise ship fantasy of fast-melting glaciers and camera-friendly caribou seen between first and second helpings at the buffet table.

But every now and then someone comes along with a story that lays a serious claim to Alaskan authenticity, advancing the Outside’s view of what life is really like in the Great Land.

With his memoir of Alaska, the Inupiat elder William L. Iggiagruk Hensley offers a coming-of-age story for a state and a people, both still young and in the making. And while there are familiar notes in the Dickensian telling of this tale, Hensley manages to make fresh an old narrative of people who arise just as their culture is being erased — be they “Braveheart” Scotsmen or outback Aborigines. His book is also bright and detailed, moving along at a clip most sled dogs would have trouble keeping up with.

Hensley’s life runs from the Alaska at “the twilight of the Stone Age,” as he says, to the petro-dominated modern state with its thriving native corporations and billion-dollar energy schemes. Hensley saw it all, and shaped much of it.

On one level, his story is first-person history, for it was in Alaska that the government tried something radically different in settling land claims of indigenous people. Instead of reservations, natives set up regional corporations — everyone a shareholder with an initial stake of land and money in what Hensley calls “the most sweeping and fairest Native American land settlement.”

On a personal level, the book is riveting autobiography. Anyone who thinks times are hard now need only consider a winter spent on an ice floor under a sod roof, and the prospect of a life-or-death journey to the outhouse.

“For me, Alaska is my identity, my home and my cause,” he writes. “I was there, after all, before Gore-Tex replaced muskrat and wolf skin in parkas, before moon boots replaced mukluks, before the gas drill replaced the age-old tuuq we used to dig through five feet of ice to fish.”

Hensley was raised just north of the Arctic Circle on the shores of Kotzebue Sound. On a clear day, he probably could see Russia from his house, for it’s a mere 90 miles across the Bering Strait. The international date line is 50 miles away, and hence the title.

The first part of the book — to me, the most fascinating — is a depiction of the nearly lost world of a North American hunter-gatherer community. Born in 1941, Hensley was raised by his mother’s cousin in a village of 300 people with no electricity, no lights, no telephones. Winter is a nine-month affair, mostly dark. Women were prized for having strong teeth, the better to crimp dried sealskins into mukluks.

The perils included not just 50-below-zero weather, but random cruelties of the primitive life. An episode of botulism — fermented walrus meat, a delicacy, went bad — killed Hensley’s adopted father.

Though it sounds harsh, Hensley writes favorably of the boy’s world of hunting, fishing and exploring under the midnight sun, and the joy of having an ancient connection to a place: “There are few people in America who can say that their forebears were here 10,000 years ago. That is a powerful thing.”

The story of his early life reads like “Angela’s Ashes” without the baroque sense of misery. The oppressors here are missionary and government do-gooders, insistent on eradicating native culture in a rush to assimilation. Hensley notes that his parents’ generation was schooled by people who forced children to write “I will not speak Eskimo” 100 times on the board.

At 15, Hensley was sent to Christian boarding school in Tennessee, where — naturally — he learned about sex and Southern cooking. He couldn’t stand the food, citing pimento cheese sandwiches in particular.

An excellent student, athlete and, by his own account, boyfriend, he went on to college at George Washington University, a series of oddball jobs and a political career in a time of tumult and possibility.

He became a Thomas Jefferson of sorts for native people after a vast oil field was discovered in Prudhoe Bay. Led by Hens ley, natives held up the state’s attempt to exploit those oil riches until aboriginal land claims were settled.

The resolution came in the form of the Alaska Native Claims Settlement Act of 1971, awarding 44 million acres of land and nearly $1 billion to the first Alaskans. It set up a series of regional corporations, some of which became Fortune 500 companies.

But the rush to modern life took a big psychic toll. Alcohol, suicide, domestic violence — the familiar litany of native social ills — prompted a long journey of the soul for Hensley. As with every other episode of his life, it is told here with a Far Northern twist and an intimacy with the land and the heart.