The science of conserving ancient Mongolian monoliths

Deer Stones, Mongolia’s mysterious ancient monuments, are the country’s most important archaeological treasures and some of the most spectacular expressions of Bronze Age megalithic art anywhere in the world. These 3,000-year-old carved stone monoliths standing 1 to 4 meters high are scattered in unprotected sites throughout northern Mongolia. Deer Stones bear elaborate depictions of flying ‘spirit deer’ with swept-back antlers and legs folded beneath their bodies—perhaps representing spirits of ancient chiefs and clan leaders. MCI Senior Objects Conservator Rae Beaubien, with the assistance of the Office of Exhibits Central Model Maker Carolyn Thome and fellows and interns, worked with a multidisciplinary Smithsonian team led by William Fitzhugh, NMNH, and Paula DePriest, MCI Deputy Director, to study, protect, and preserve these monuments in their natural settings, and to capture their pictorial information with 3-D laser scanning. This information will be available virtually through the Smithsonian Web to researchers studying the Deer Stone iconography. Our 3-D laser scans serve also as a snapshot of the condition of the stone monuments, with resolution in the millimeter range, pinpointing not only the surface decorations but also the physical evidence of damage. Using GIS techniques, we can wrap a sketch map marked with today’s visible damage – bird droppings, lichens, and surface erosion – like a skin around the 3-D image. Then we can ask if a type of stone damage is correlated with a particular feature – a concave surface, a roughened stone texture, a heavily carved area, a patch of lichen or fungi, etc. Over time we can follow changes in the stone, to see how rapidly the damage increases, and if the organisms come and go either on their own, in concert with climate changes, or after a treatment to control them.