More than 700 million years ago, the Earth was plunged into a state that geologists call “snowball Earth”, when our planet was entirely encased in ice. This happened when the polar ice caps expanded so far that they joined up around the equator. More than 700 million years ago, the Earth was plunged into a state that geologists call “snowball Earth”, when our planet was entirely encased in ice. This happened when the polar ice caps expanded so far that they joined up around the equator. Earth Sciences Phys.org – latest science and technology news stories