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Tribal and state partners collaborate to digitally preserve petroglyphs in Michigan's Thumb

Media Contact: Misty Elliott 
517-335-9847 |

October 12, 2018

LANSING, MICH. – Tribal and state partners are working closer than ever to care for and preserve more than 100 petroglyphs carved into a large sandstone outcrop on the Cass River floodplain using laser technology.

“We created digital models of the Sanilac Petroglyphs with harmless pulses of light that detect and measure the 3D world,” said Stacy Tchorzynski, an archaeologist at the State Historic Preservation Office (SHPO) and project manager for the Sanilac Petroglyphs. “This is an ambitious collaboration between SHPO and MDOT, in partnership with the Ziibiwing Center of Anishinabe Culture & Lifeways, Saginaw Chippewa Indian Tribe of Michigan and the Michigan History Center, DNR.”

MDOT specialists used terrestrial LiDAR (Light Ranging and Detection) and close-range photogrammetry–overlapping detailed photographs–to build digital models that will help document the site and track its preservation. The sandstone petroglyphs are fragile and subject to weathering and other environmental and human forces.

“People worldwide have carved images into stone to honor their ancestors, record teachings and mark important events,” Tchorzynski said. “Sanilac Petroglyphs Historic State Park has Michigan’s largest known collection of carvings, which likely date from within the last 1,400 years.”

This technologically advanced historic preservation project is featured on the 2018 Michigan Archaeology poster. The free poster is available from SHPO upon request and will be available (while supplies last) at Archaeology Day at the Michigan History Center in Lansing on Saturday, October 13.

Archaeology Day has activities for people of all ages, including spear-throwing, a scavenger hunt, pinch pot making, and mock excavations. Author Chris Winters will present “The Story of the Edmunds Fitzgerald in Pictures,” and more than 50 archaeologists will be there to talk one-on-one with visitors about their Michigan-based research projects. New this year is the Archaeology Roadshow, where visitors are invited to bring an object to show a panel of experts to learn more about it (no monetary values will be given).

Find more information about Archaeology Day and see the 2018 Michigan Archaeology poster at