Arizona's Conscience Rocks: Look, Don't Take

The National Park Service estimates that about a ton of fragments of petrified wood is stolen by the 600,000 annual visitors to Arizona's  220,000-acre Petrified Forest National Park. The ones seized and returned are piled up in th epark and are called "conscience" rocks. 

"Once it's removed from the original place, the damage is done," Park ranger Kip Woolford said. "There's no way to put it back where it originally came from." The stones have been taken "out of their context," Woolford said. They no longer have scientific value and are placed on the piles. There's no way to know for sure how much is taken.[...] the museum's collection of letters sent with conscience rocks has about 1,200 pages written between the 1930s and now. [...] The minimum fine for stealing petrified wood or pottery shards or any archaeological artifacts is $350. [...]  The typical response from visitors who are caught: "'It's just a small piece. I thought it was OK,'" [...]  visitors may pick up the petrified wood to look at it. That's fine, as long as they put the rocks back where they found them.

The analogy with historic relics is clear.

Sources: 
'Rocks with a conscience pile up at Petrified Forest' Arizona Daily Sun 27 Oct 2012.
'Have a guilty conscience? Put the rock back' Doubtful News 5th Nov 2012. 
'Petrified Forest's 'conscience' rocks returned to park' Boulder Daily 5th Nov 2012.
'Petrified wood stolen by visitors, piles up after losing scientific value at Petrified Forest' The Associated Press, November 04, 2012.