Scientists have discovered the "fossilized fingerprint" of a chunk of seafloor that was hiding beneath the Pacific Ocean in Earth's mantle.
A new study shows that this fingerprint corresponds to a slab of Earth's crust that began sinking into the mantle approximately 250 million years ago, at the dawn of the age of dinosaurs (252 million to 66 million years ago). This slab once formed part of the seafloor in the southeastern Pacific and could help explain a strange gap in the lowermost sections of the mantle — the middle layer of Earth's crust that wraps around the planet's core.
