The number of daily visitors to the Joggins fossil cliffs in Nova Scotia has doubled, just weeks after UNESCO declared it a world heritage site. But the new visitors are taking souvenirs of their trip, like rocks or even fossils, and that's a problem.

The Joggins cliffs are known for having the best record of life from the coal age -- about 300 million years ago.

Fossils of nearly 200 species, including animals, reptiles and plants, have been found there.

"That's literally truckloads of material of coming off the beach," Jenna Boon of the Joggins Fossil Centre said.

The cliffs have been protected for decades and it is illegal to remove anything from the site. Even a small stone could reveal important information about the Earth's past.

"The little bit of knowledge that we gain from every fossil that we find adds to the story of Joggins," chief interpreter Brian Hebert said.

Site monitors have stepped up beach patrols -- not necessarily to enforce the law, but to educate visitors.

"It's a little bit disappointing because you want souvenirs, but I understand it, because if everyone were to take things away there would be nothing left," one woman on the beach told CTV.

The cliffs are in exclusive company -- there are only 14 other world heritage sites in Canada and 855 sites worldwide.

There is only one other world heritage site in Nova Scotia -- the old town of Lunenburg.

With a report from CTV's Denelle Balfour