In countless grade-school science textbooks, the Earth’s mantle is a yellow-to-orange gradient, a nebulously defined layer between the crust and the core. To geologists, the mantle is so much more than that. It’s a region that lives somewhere between the cold of the crust and the bright heat of the core. It’s where the ocean […]

Around A.D. 79, Roman author Pliny the Elder wrote in his Naturalis Historia that concrete structures in harbors, exposed to the constant assault of the saltwater waves, become “a single stone mass, impregnable to the waves and every day stronger.” He wasn’t exaggerating. While modern marine concrete structures crumble within decades, 2,000-year-old Roman piers and […]