Mesogaea ( from Greek méso- "middle" + gaia "earth" ) is the name for the formation of the continents during the events of Blindside. It occurs millions of years after Homo sapiens become extinct but before the formation of Pangaea Ultima. At this time, Afro-Eurasia and the Americas approach each other, cutting the Atlantic ocean significantly but not to where the continents can be seen from each other's horizons. Nyxis is alive during what the world population considers the fifteenth century, and it isn't until the sixteenth century that an exploration team successfully circumnavigates the large expanse of the Pacific Ocean.
Mesogaea is a scientific term; people usually refer to the world as "Earth."