Some longtime residents of Big Sur figured nature hadn’t finished with them this year. Over the weekend, they were proved right.

With a loud boom and a cloud of dust, part of a mountainside slid into the Pacific Ocean on Saturday night, swallowing roughly a third of a mile of Highway 1 and rearranging some more of Big Sur’s dramatic coastline.

“No words needed but here’s a few,” began a Monday tweet from Caltrans District 5. “Millions tons of rock/dirt, about 1/3 mile of roadway covered 35-40 feet deep.”

“Mother Nature hard at work,” Caltrans added.

Aerial photos and video of the massive landslide show a huge tongue of earth reaching into the sea in the Mud Creek area of southern Big Sur.

“Some people had a feeling it would happen…. Once the land dries it goes more than when it’s wet,” said Megan Handy, whose family owns Treebones Resort, about two miles north of the slide.

Nature’s weekend show is just the latest challenge for Caltrans crews along the Central Coast, where the wettest winter in decades caused Pfeiffer Canyon Bridge in Big Sur to fail, closed parts of Highway 1 and led to the partial collapse of a section of heavily traveled Highway 17.

“ ‘Unprecedented’ would be a good word to use,” Caltrans District 5 spokesman Jim Shivers said of the damage. “Things are better now, but we were basically working seven days a week from early January through early April.”

The weekend’s slide capped a series of smaller slides in the area that had closed a part of Highway 1.

Crews working to clear the previous slides had to abandon their work last week after engineers noticed that the hillside looming above them continued to move, Shivers said.

“We were fearful because there was potential for additional slides. We didn’t think it would be the magnitude of this,” he added.

This winter’s storms had caused at least $1.3 billion in damage to state and local roads and highways, according to an estimate in mid-April, Shivers said. That total is likely to climb after last weekend’s collapse, he said.

One contractor was killed during work on Highway 17 in February.

Caltrans couldn’t say how long it would take to rebuild. But Handy said locals are guessing it will be at least a year, dashing hopes that the popular coastal highway would completely reopen this year.

“The highway’s not even there under it. The whole mountain just slid,” she said.

Although storm damage closed Highway 1 north and south of Treebones, the resort has remained open because guests can reach it from the east by driving a winding mountain road.

“Generally the people who live here are resilient people,” Handy said. “They have their own power. They grow their own food. So they’re like, ‘OK, we’re going to make it work.’ ”

“But it’s definitely been challenging and disheartening,” she added.

joseph.serna@latimes.com

bettina.boxall@latimes.com