TRAVERSE CITY -- They aren't certain, but underwater archaeologists say they may have discovered a boulder with a prehistoric carving in Lake Michigan's Grand Traverse Bay.
The granite rock has markings that resemble a mastodon -- an elephant-like creature that once inhabited parts of North America -- with what could be a spear in its side, say divers who have seen it.
They came across the boulder at a depth of about 40 feet while searching for shipwrecks in June, said Mark Holley, a scientist with the Grand Traverse Bay Underwater Preserve Council.
"When you see it in the water, you're tempted to say this is absolutely real," Holley said Tuesday during a news conference with photos of the boulder on display. "But that's what we need the experts to come in and verify."
Specialists shown pictures of the boulder have asked for more evidence before confirming the markings are an ancient petroglyph, said Holley, an underwater archaeologist who teaches at Northwestern Michigan College in Traverse City.
"They want to actually see it," he said. Unfortunately, he added, "Experts in petroglyphs generally don't dive, so we're running into a little bit of a stumbling block there."
Among those withholding judgment is Daniel Fisher, curator of the University of Michigan Museum of Paleontology, who has studied human interactions with mastodons. He has examined a couple of the photos and is waiting for more.
"The difficulty I saw was that the features of what's interpreted as an engraving were so subtle, and they're not the only thing on the boulder," Fisher said in a phone interview.
Also, he said, mastodons are not known to have ranged into northern Michigan, although fossil remains have been found in the southern part of the state. They became extinct about 10,000 years ago.