he Exxon Corp. spent $400 million rearranging the mountainside above this one-stoplight town into what was to have been the nation's first commercial oil shale development. Across the Colorado River on a bluff overlooking Parachute, a new town with broad streets, modern houses, apartments and a trailer park--a model of western boomtown management--was taking shape with breathtaking speed.

But on Sunday, it all came to a stunning halt.

Exxon, sobered by doubled costs and a soft world market for oil, said it was pulling the plug on the $5 billion Colony Oil Shale Project.

Nothing could have surprised people more, because some of them had been hired as recently as Friday, and more were on their way from across the country to take promised jobs.

Half of the 2,100 workers at the Colony project were laid off Tuesday. The rest will stay only long enough to complete what Exxon officials have termed "an orderly shutdown."

But there was nothing orderly about the jolt that Exxon gave to Michael Meline and his fellow workers. As the town of Parachute ponders a future without Colony, the men and women who were building it have begun their exodus.

Meline stood at a pay phone in the Valley Cafe yesterday talking to a man in Houston. "I'm all packed up and ready to go to another job," he said. "I'm willing to relocate anywhere, sir."

Meline's resilient family ate their last Colorado breakfast at a nearby table, while Meline, with some suggestions from Brown & Root Inc., the project's general contractor, patiently stayed by the phone seeking work. "Toward Baton Rouge? Okay, I'll call him."

Meline dialed again. "This is Michael Meline. I was wondering if you need a rock buster."

An hour later, after just three months in Colorado, Meline was on the road to Louisiana with his wife, brother, three children, their last $600, and no promise of work.

Before he left, he turned to another person in the cafe. "I figured, man, this was going to be the spot," he said. "The boom."

That's what everyone thought. A year ago, the area was filling up with people from Michigan and Alabama and Texas who had come for the promise of steady work and pay of up to $16 an hour. Because there was little housing then, many of them camped along the river.

The laborers, used to the insecurity of construction work, talked of Colony as their retirement job and looked forward to settling their families in the splendor of the Rockies. The town's population quadrupled, school enrollment more than tripled and, seemingly overnight, a shining new community was overlaid on Parachute's faded facade. Many of those who had camped a year ago found places to live in Battlement Mesa, Exxon's new town.

As the word of Exxon's totally unexpected decision spread through town on Sunday, an orgy of drinking and anger and occasional vandalism broke out. Within days, the anger was overwhelmed by the numbing reality of hunting work in a recession--and, among some permanent residents, by the cocky optimism of a town that has seen it all before. In Parachute, there is an eerie feeling that the boom-and-bust cycle that governs the history of the West is at work again.

A week ago, huge earthmovers were at work at the Colony site 15 miles up the creek from Parachute. Now they are being hauled down the mountain on long trucks, a grinding procession of broken dreams. Behind them on Parachute's dusty streets come the moving vans and RVs and cars pulling U-Hauls, filled with the possessions of families wondering how their fortunes could have changed so quickly.

Here on the western slope, oil shale has been an unfulfilled promise for decades, but Colony was no ordinary project. A joint effort between Exxon and The Oil Shale Corp. (TOSCO), Colony had become the symbol of shale's coming of age--and the West's ability to manage rapid growth.

For almost two years, it had the financial resources of the world's largest oil company behind it and an enormous sense of momentum, and that was enough to persuade even the skeptics that this time the promise was real.

"There was always an attitude of skepticism here," said Rebecca Mack, who arrived six years ago as a radio writer and now works for Chevron Oil Shale Co. "It was a feeling of, 'I'll believe it when I see it.' But that was the thing about Exxon. You were seeing it. There was a lot of dirt being moved. It was like they were building the pyramids up there."

A light rain was falling Tuesday as Don Bentz struck a match and lit another cigarillo. He stood outside his new modular home in Battlement Mesa, leaning against a pickup truck with three rifles hanging on the gun rack.

Bentz purchased his home in March for $35,000, and his wife was planning to move down in mid-May. On Tuesday morning, Bentz picked up his last check.

"I raised seven kids in my lifetime and saved enough to buy a house, and goddamn it, in 30 days I lost it," he said. "Sell it? Who to?"

Within days after Exxon's announcement, Battlement Mesa, which was being built to accommodate 24,000 people, had become a community silent with insecurity.

In the mobile home park, cars stood outside new homes, but the only sign of life was from those packing up to leave. In the camp housing single workers, overturned garbage pails, a broken fence and strewn beer cans were a reminder of Sunday's reaction. Moving vans chugged past freshly poured foundations, even as construction crews continued to work on apartments and houses that may never be occupied.

Some people here remain optimistic. They point to Union Oil Co.'s decision to continue its smaller shale project and to several other oil companies, including Chevron, that are in the process of establishing major projects. "The area has seen boom and bust for 50 years," said Ralph Freedman, Parachute's town administrator. "I really don't think the world's going to come to an end here."

But the question asked repeatedly here this week about the future of shale is, if not Exxon, who? Until that question is answered, the entreprenuers who flocked here to take advantage of the boom will nervously try to ride out the shock.

Until this week, Pat O'Neill ran one of Colorado's busiest saloons; now he predicts that Colony's departure may cost half his business. Another man opened a car dealership last week and had not even taken possession of his inventory. Still another bravely opened a new motel on Monday.

Parachute feeds now on rumors and conspiracy theories that all end with Exxon's--or someone's--return in a relatively short time. "It's good shale property," said Marvin Wambolt, the town's building inspector. "Eventually someone's going to come in and pick it up."

But for some people, the next boom may be too late. Tony and Carol Ortolani left Wilkes-Barre, Pa., last week for Parachute with the promise of a job. They borrowed $1,500 to make the trip and left their children with relatives until they could get established.

On Tuesday night they arrived in Parachute. A stranger gave them the bad news, but they refused to believe him. "I've got a letter of reference," Tony protested. "This can't happen in one day."

His wife sat in O'Leary's Pub in disbelief. "You mean we don't get a new house, Tony? You mean we don't get a new yard? Tony, there's nothing to go back for. Tony, How are we going to get our kids?"

"Carol," said Tony, "shut up. I don't want to hear it."