Preserving the Past in 3D

A limestone boulder with petroglyphs carved into it sits inside a rock shelter with a view toward the Mississippi River floodplain, below. One of the carvings is of a superhuman eye with a cross-in-circle motif at its center. Photo by Alleen Betzenhauser

Illinois State Archaeological Survey graphic design manager Mera Hertel and senior research archaeologist Steve Boles (not pictured) measure and record data.
Photo by Alleen Betzenhauser

MONROE COUNTY, Ill. – It isn’t often that you get a sunny, 70-degree day in the beginning of February, especially less than a week after a record-setting cold snap plunged most of Illinois into subzero temperatures. We certainly aren’t about to waste the fine weather, even if it means a day lugging heavy equipment up a steep ravine in the bluffs overlooking the Mississippi River.

John Lambert – visiting archaeological spatial analyst, Illinois State Archaeological Survey

A local landowner leads our team of archaeologists past a small waterfall up to the top of the bluff, where two rock shelters contain a number of ancient petroglyphs. These designs were pecked and ground into limestone boulders sometime between A.D. 1050-1400, during what archaeologists call the Mississippian Period. This era saw the founding of the American Indian city of Cahokia, some 30 miles north of here.

Alleen BetzenhauserPhoto by Rob Rohe

Luckily, our guide has tied a series of ropes between trees to help us haul our gear, and ourselves, up the steep, slick slope.

The team used a portable 3D scanner to recreate the details of a hand petroglyph from a site overlooking the Mississippi River in Monroe County, Illinois.
Photos by Steve Boles (top) and John Lambert (bottom)

When we reach our destination, we take a moment to catch our breath. It’s easy to appreciate why past people chose this spot for their petroglyphs: It has a commanding view of the great Mississippi River floodplain below. A limestone outcrop in one shelter is emblazoned with the imprint of a hand – a tangible, human link to the people who created these icons nearly a millennium ago. A limestone boulder in a nearby rock shelter bears glyphs of a superhuman eye, concentric circles and other, more enigmatic motifs.

John Lambert scans a 1,000-year-old bowl using the portable, structured-light scanner.
Photo by Jennifer Goldman

This site and others like it are at risk from erosion, urban development, and damage by looters. That’s why we’re here armed with a new tool: a portable, structured-light 3D scanner.

The petroglyph site sits atop a bluff overlooking the Mississippi River. John Lambert walks down the steep slope below the rock shelters.
Photo by Steve Boles
Summary
Preserving the Past in 3D
Article Name
Preserving the Past in 3D
Description
It isn’t often that you get a sunny, 70-degree day in the beginning of February, especially less than a week after a record-setting cold snap plunged most of Illinois into subzero temperatures.