The huge rock that fell off a steep slope in Lawrence County early last Friday morning and tumbled, onto U.S. 52, is an example of erosion at work. One driver suffered minor injuries after slamming into the unexpected object that closed all four lanes of the highway along the Ohio River, and had to be cleared by the Ohio Department of Transportation crews over the weekend.
Ohio Department of Natural Resources senior geologist Michael Hansen has documented many state rockfalls in more than four decades of work. He says there are several factors that cause pieces of sandstone and limestone to tumble to the pavement from the steep slopes of southeastern Ohio.
The force of gravity propels these massive rocks quickly downslope once a fracture occurs due to the freezing and thawing of moisture that seeps into porous rock faces. Heavy rainfall, which occurred in southeastern Ohio over five days last week, likely contributed to erosion and added weight to the rock that easily absorbed water through the porous surface.
Rockfalls can be deadly–one in Lawrence County in 1986 killed a motorist. Rocks have crushed buildings in southeastern Ohio, where the terrain favors such potential natural disasters.