Authorities at the Grand Canyon are looking for vandals who spray-painted a rock near an overlook on the South Rim.

Park spokeswoman Kirby-Lynn Shedlowski says a visitor photographed the rock with "Evans 16" spray-painted in black, and a man and woman walking away from it on May 22.

The man was wearing a reddish-pink T-shirt and brown pants with a gray sweater tied around his waist. The woman had on jeans and a long-sleeve, camouflage-print shirt.

Defacing a natural feature is a federal offense that carries jail time and fines.

Actress Vanessa Hudgens paid a $1,000 fine for carving into a rock in the national forest surrounding Sedona this year. The damage was repaired, but that's not always possible.

A large carving at Arches National Park discovered in April was so deep officials weren't sure it could be erased.