Sometime after 8:30 p.m., a sizable chunk of the basalt-like rock that's part of the Palisades Interstate Park cliff face near a scenic overlook let loose, carving a path of shattered rock down to the edge of the river.
Susanne and Richard Ostrowski, who live in a fifth-floor condo across the river in Yonkers, were watching TV on Saturday night when they heard a loud, rumbling sound. They saw a plume of white dust rising from the base of the cliff.
"It sounded like a military plane flying low overhead," Susanne told Newsday on Sunday morning. "I didn't know what it was. I've lived here almost 13 years, and I've never seen anything like that."
State Police in New York and New Jersey said they didn't receive any reports about the rockslide, and it doesn't appear that anyone was injured. A rest stop is located above the section of cliff wall that collapsed.
Rockslides happen every few years or so, according to the Palisades Interstate Park website.
In 2005, a rockslide at the park consumed about 80 feet of Alpine Approach Road, damaging a golf course and parking lot.