The Herbert C. Bonner Bridge, a multimillion-dollar, three-mile-long span of concrete and steel, arches stolidly across Oregon Inlet, connecting, at least for the time being, two rebellious islands on North Carolina's Outer Banks.

The Islands are shifting southward at an average rate of 10 to 20 feet a year, and the inlet between them is leaving the bridge behind, in danger of collapse. Millions of dollars have been spent to rebuild the pilings on one side, while on the other, almost half the bridge now spans dry land.

The islands are rebelling, it is said around these parts, against the arrogance of engineers and the idea that man's technology can tame the sea and the sand.

For more than 100 years, settlers lived in harmony with these narrow, windswept ribbons of beach, barrier islands that shelter the mainland from storm-driven seas. They built their houses well back from the shore, and knew enough to hide from hurricanes.

But in the last few decades, a tide of sun-seeking vacationers has swept the coast. They have built homes on quarter-acres of oceanfront, the waves lapping their asphalt driveways. They have ordered roads and bridges, water pipes and septic systems.Motels, highrise condominiums, fast food joints and mobile home parks have sprouted.

But the islands resist. Massive erosion is destroying hundreds of houses and large stretches of federally owned seashore each year.

Geologists studying the coastline predict that the next hurricane will wash away thousands of homes. And, they say, although millions of dollars have been spent on sand dredging, jetties, sea walls and articial dunes, these engineering projects have only hastened erosion.

Bonner Bridge is the latest battle-front in a long war between man and ocean along the Carolina coast. The Army Corps of Engineers wants to build two jetties, immense walls of rock, more than a mile out to sea, to "stabilize" the inlet. The project would cost more than $75 million and require a $2 million annual outlay to counter the extensive beach erosion that would result.

Corps officials say the project is necessary to protect the local fishing industry, including a new food-processing center financed by the state. They add that it also would protect the Bonner Bridge.

However, recent studies by two North Carolina geologists, Orrin Pilkey and Stanley Riggs, contend that the jetties would destroy the "dynamic equilibrium" of the coastline, causing massive private property damage and disrupting the 75-mile-long Cape Hatteras National Seashore.

"

Riggs also said he fears that stabilizing the inlet will render it inflexible to storms, and thus increase the chance that another inlet would be blown through the island by water pressure. This could result in a violent ocean channel through the middle of nearby subdivisions at Nags Head and Rodanthe.

Riggs' solution to the "migrating inlet" is to let it mosey along, abandon the bridge if necessary and restablish ferry service, an unpopular proposal among development-oriented islanders whose economy depends on tourism.

However, Cape Hatteras Superintendent William Harris is concerned that tourism might suffer in the long run if the corps project is built. Already, 60 percent of the seashore's land is eroding, some beaches up to 40 feet per year. Entire stretches have disappeared under water, so that the public no longer has access to an unbroken shoreline.

The U.S. Park Service, which must grant a permit before the project can proceed, has rejected one corps environmental impact statement.

"The corps was unresponsive to our concerns," said Harris, who said he fears that 10 miles of federal beaches could be affected, while the corps plans to replenish only three miles.

Corps officials, however, dispute the geologists' contention that the inlet should inexorably move southward. The jetties, they say, will be effective aid to navigation, and the beaches will be restored through pumping sand.

Whatever the outcome of the Oregon Inlet dispute, it is only part of a much broader philosophical dilemma. The Carolina coast is littered with monuments to the futility of fighting the sea: Bridges that go nowhere, highways cut off by the ocean, cavedin houses, broken piers, tree stumps overwhelmed by the beach.

And yet millions of Americans live near the coast, and more and more of them crave a week, or even a weekend, at the beach.

And don't they have a right to it? And why shouldn't the government subsidize their pleasure?

So the government reasoned, when, in the 1930s, it put the Civilian Conservation Corps to work building a massive line of artificial dunes along Cape Hatteras.

"We thought the beach would start growing," Harris said. "So we built dunes as fast as we could, and spent $20 million rebuilding them over the years. Now we've lost 600 to 700 feet of beach in some areas."

The Park Service discovered in the early 1970s that artificial dunes did not hinder erosion, but accelerated it. The islands, geologists found, have been naturally migrating toward the mainland over thousands of years as the sea level rises because of melting glaciers.

During storms, the waves washed sand over the narrow islands, eroding the ocean beach and building up the inland shore. The dunes prevented this natural overwash, so the erosion continued without a compensating buildup.

The Park Service has now declared that it will not attempt to stabilize any part of the federally owned shore-line. Thus, it announced in April that it will let the historic Cape Lookout Lighthouse, threatened by erosion along Barden Inlet, slide into the sea. The Park Service rejected a Corps of Engineers proposal to protect the structure with $3 million revetments. Local citizens are protesting the decision.

Over the next few years, if the Park Service allows overwash, storms could wipe away large parts of the eight villages within the Cape Hatteras National Seashore. Many houses are already falling into the sea, and yet, all along the shore, on the very edge of eroded banks, new homes are being built and real estate signs compete for space.

At Rodanthe, a few miles south of Oregon Inlet, the island is less than a quarter mile wide, and the beach is eroding 25 to 30 feet a year. Riggs predicts that an inlet will break through there in the next fierce storm. "This is one of the most hazardous pieces of property in the country, next to the land over the San Andreas Fault," he said.

The opening and closing of inlets is a natural process that should not be hindered by human development, he contends, because it is through inlet formation and the resulting tidal deltas, that the islands naturally rebuild themselves.

Frank Lorenzo, a real estate agent, has an $80,000 oceanfront house for sale in Rodanthe. "Rodanthe is very narrow. It is dangerous to have a house to reclaim what's hers . . . It's 'buyers beware.'"

However, Lorenzo says the Outer Banks has other areas safe build on, which is acknowledged by the geologists. "I've been here eight years," said Lorenzo, who moved from Brookly. "I'm not the least bit concerned."

For 19 years the islands have not had a major hurricane, although hurricanes occurred every two or three years in the past. "We're in a period of unusual quiescence," says Pilkey, a Duke University geologist. "People are being lulled into overconfidence."

An example he cites is the four-story Holiday Inn in Wrightsville Beach. The motel was built in 1966 on land that once was an inlet. Another inlet will eventually pop open there, he predicts. The motel is now lapped by the waves during high tide.

Holiday Inn officials say they are not worried. The towns of Wrightsville Beach and nearby Carolina Beach, however, have recieved millions of dollars from the Corps of Engineers and the state to pump new sand on their shores.

Pilkey and other geologists contend that such artificial measures accelerate erosion, and that public money should not be spent to protect fool-hardy private development. Lim Vallianos, a corps engineer, disagrees.

"It's not the fat cat on the beach we're protecting," he said. "These beaches are used by the public, and there's a public interest in maintaining a viable economy here." CAPTION: Picture 1, Erosion eats away at the old state highway that runs near the Herbert C. Bonner Bridge on North Carolina's Outer Banks. The Problem is widespread and growing. By Frank Johnston - The Washington Post; Picture 2, Dome House, just south of Nags Head in North Carolina, sits precariously on its beach-front site, which is being clawed at by the encroaching ocean.; Map, no caption, By Dave Cook - The Washington Post; Picture 3, The sea laps at a seawall protecting homes at Wrightsville, N.C.; Picture 4, Sanbags shore up the dunes at Ocracoke Island, North Carolina, as surfers go about their pleasure. Geologists see a loss of 20,000 acres of beach by 2000. Photos by Frank Johnston - The Washington Post