Gravestones get special care Gravestones get special care By Beth Wohlberg Camera Staff Writer Lichen creeps into the cracks and crevices of old gravestones at Columbia Cemetery in Boulder, slowly destroying the intricately carved rocks.
Acid rain eats away the rocks' surfaces.
Freezing and thawing water trapped in small holes create fissures. Nature isn't kind to the tombstones here that mark the resting places of people who died, some more than 100 years ago. But by drawing on geology, physics, chemistry and biology, Mary Reilly-McNellan and her crew of volunteers have found ways to slow down the inevitable crumbling of old stones. Sandstone, limestone and marble will wick up water from the ground. If it freezes and thaws, expands and contracts, there will be cracks in the rock.