For 45 years Gardiner and Carolina Means have lived happily on their 70-acre country hideaway in Fairfax County while all around them, modern suburban sprawl took shape.

A placid oasis of open land the property -- within minutes of Wolf Trap Farm Park -- has risen in value to more than $2 million as developers in fast-growing Northern Virginia eyed the site covetously. "We have to shoo them away," says Caroline Means.

Now the Meanses have placed the land permanently out of reach.

Gardiner, 84, a New Deal economist who came to Washington in 1932, and Caroline, 80, an economic historian have given 50 acres to the Northern Virginia Regional Park Authority for public use.

In the future the Meanses, who have no children, will give the park authority the remaining 20 acres, along with their white clapboard house, part of which is a one-room log cabin dating to 1760.

"You can't take it with you," Caroline Means says cheerfully. "It's given us a lot of satisfaction."

Officials at the park authority can scarcely contain their excitement. "This is a very important acquisition," says executive director Darrell G. Winslow. "It would be difficult to find a property like this so close in, and probably prohibitive to buy."

The Meanses set about acquiring the land in 1935, shortly after Gardiner had been recruited by one of President Franklin D. Roosevelt's top aides, Rexford G. Tugwell.

Their original goal was quite modest. "We thought, if we could just find an acre to pitch a tent -- nothing more than that," said Caroline Means (Caroline P. Ware, professionally). But after looking at various locations that proved unsuitable, she said, "We began to think we might move out of the city and not just pitch a tent."

A real estate agent guided Mrs. Means to a farm on Beulah Road, just north of the town of Vienna. "It was the first of May," she said. "The apple orchard was in full bloom. The field was in spring wheat. The whippoorwill was singing his song. 'It's time to plant your corn.'

"I went back to town and called Gardiner and said, 'I found a farm. Shall I buy it tonight or do you want to come out and see it?'"

About a half a mile away is the authority's 50-mile linear park along what was once the Washington & Old Dominion Railroad's line. Winslow said campers and hikers using the trail will be able to use the park as a stopping place.

If they hadn't acted quickly, the property might have slipped through their fingers, for another buyer was just as eager, but was trying to whittle $500 from the $7,000 price. "He was furious when he discovered it had been sold," said Mrs. Means.

To the Meanses, their place has been, simply, "The Farm." They never gave it a fancier name. In the beginning they had sheep and some cattle, and later planted some crops. Lately they have let some of the open areas grow up to shield out encroaching suburbia at the bottom of the valley.

For Gardiner Means, The Farm has meant "peace and quiet and elbow room and good neighbors." And it was in easy commuting distance to the big metropolis. He remembers it was exactly 17 miles to the Bureau of the Budget, where he worked during the height of the New Deal.

For Caroline Means, the place has "provided a kind of perspective. I used to say, when you're in the city, you have to do things in minutes or hours. In the country, you get things done by seasons, a little bit by the months or weeks. The country doesn't oblige."