Why Philly has so many sinkholes
- Written by Laura Toran, Professor of Environmental Geology, Temple University
Sinkholes form when underground rock dissolves or sediment washes away and the surface collapses.Luis Diaz Devesa/Moment Collection/Getty ImagesIn early January, a giant sinkhole formed at an intersection in the West Oak Lane neighborhood of North Philadelphia after a water main break. Just two weeks earlier, the city reopened a section of the...

