Two continent-sized structures named Tuzo and Jason sit nearly 1,800 miles beneath the surface of the Earth — one beneath the Pacific Ocean and the other beneath Africa — and have been holding their shape for at least 200 million years, in two of the largest single structures ever identified inside any planet, despite no one on the surface ever having seen them

The deepest hole humans have ever dug, the Kola Superdeep Borehole on the Kola Peninsula in Russia, reached approximately 12 kilometres before the heat, pressure, and engineering challenges of drilling overwhelmed the equipment. Earth’s mantle begins at approximately 35 kilometres depth and continues to approximately 2,890 kilometres — 1,800 miles — where it meets the [...] The post Two continent-sized structures named Tuzo and Jason sit nearly 1,800 miles beneath the surface of the Earth — one