DEATH VALLEY NATIONAL PARK, Calif. (AP) -- A wooden chest filled with gold and silver coins and believed to have belonged to Gold Rush pioneers actually contained items with 20th century markings and photographs developed after 1856, park rangers say.

The trunk was allegedly removed from Death Valley National Park in November by amateur archaeologist Jerry Freeman. He said he was retracing the steps of the Lost Pioneers of 1849, who left the Midwest in search of gold and ended up in the California desert.A manifest in the trunk led Freeman to believe it was buried on Jan. 2, 1850.

"The park can claim what it likes, but I can't be swayed," Freeman told the Daily Independent of Ridgecrest on Wednesday. "I was told by some that once I moved that chest the park would never validate the find. My reputation has been ruined."

Two tintype photographs inside were developed with a process that wasn't patented until 1856, and two bowls had 1914 manufacturers' marks, Death Valley park superintendent Richard Martin said Wednesday.

Tests on adhesive samples showed 20th century polymers were present in three items. The tests were conducted by conservators from the Smithsonian Institution in Washington, D.C., and the Western Archaeological and Conservation Center.