EXPLORATION : A Head Start on Columbus Day No. 1,000 : Some majestic giants of the New World will stand guard over a cradle of history.

John McElroy is a silver-haired scholar who has spent countless hours of the past two years in the grip of a thoroughly improbable idea. It came to him one day out of nowhere and won’t let him be.

It involves stately redwood trees, visions of world harmony and Christopher Columbus.

When the 500th anniversary of Columbus’ discovery of America was still a few years away, McElroy, an English professor at the University of Arizona, began wondering how it would be celebrated.

His interest in Spain dates back to his days as a Fulbright scholar there in the late 1960s. McElroy’s memory was particularly keen about Galicia, a wet region of northwestern Spain that reminded him of Northern California.

Thinking about that, he came upon his idea: “Wouldn’t it be great to plant 500 California redwood trees there, as a gift from the New World back to the Old World?”

McElroy started pounding the typewriter. He racked up a long list of polite refusals of help from impressive sources, including some big corporations and President Bush.

His break came in September, 1990, when he wrote then-California Gov. George Deukmejian, who forwarded the letter to Hal Walt, director of the California Department of Forestry at the time. Walt offered a forester to give technical advice and the redwood seedlings--but, he wrote, McElroy would have to do everything else.

“That was all right with me,” said McElroy, 57, who, early in his academic career, spent 12 painstaking years editing a biography of Columbus by Washington Irving. “Walt really put a floor under the project.”

Since then, McElroy has formed the Columbus Grove Gift Corp. and has made two trips to Spain to work out details. He has gotten critical support from the Spain ’92 Foundation, an arm of the Spanish government coordinating 500th-anniversary programs between the United States and Spain.

The group’s leaders were particularly pleased to learn that it would take 500 years for the young trees to grow to maximum height. That meant the redwoods would be fully flourishing by the 1,000th anniversary.

“We thought this was more impressive than any other kind of monument because it is a living tribute, a gift from the U.S. to Spain that will serve as a lasting link between the two countries,” said Aimee Metzner, project manager for Spain ’92.

McElroy and Rafael Mazarrasa, executive director of Spain ‘92, spent more than a year “wheedling and nagging,” McElroy said, to get the 2.5 acres where the trees will be planted.

The site, in the Galicia municipality of Poyo, overlooks the Atlantic Ocean and is within view of Pontevedra, the city where Columbus’ flagship, the Santa Maria, was built.

The community of San Xoan and the government of Galicia manage the land communally, and getting permission to use it required consent of both.

“I was surprised, not so much by the acceptance, but by the enthusiasm I was greeted with,” McElroy recalled. “The magnificence of these trees excited the people. In their minds, redwoods are part of the fabulousness of America.”

A major hurdle remains. McElroy needs an estimated $228,000 to cover expenses. But Columbus Grove is well-connected. The project’s fund-raiser is Donald P. Crivellone, who raised money for the 1984 Olympic Games in Los Angeles.

The ceremony is to take place Dec. 4, 1992. McElroy will be accompanied to Spain by 25 American youngsters, all 4-H Club members, representing various regions of the United States. In Spain, they will meet with 25 Spanish children who will join them in the planting of Columbus Grove.

Although McElroy is well aware that some activists, particularly American Indians, view Columbus’ arrival in America as the beginning of bad times on the continent, he sees his project as one that looks to the future, not the past.

“We’re creating divisions in this country by brooding about the sins of our forefathers,” he said. “I want this project to represent a new 500 years for the human race, a coming together of mankind that began when Columbus linked up the two continents.”

He is confident of success: “I just have an intense desire to plant these New World trees in Old World soil, and from Day 1, I’ve gone ahead with the faith that it would happen.

“So far, it has worked.”