If Earths core cooled down completely what would be the effects on the Formation of Earth? I think that eventually, over millions of years, the enitre surface of the Earth would be covered in water, a huge ocean. There would be no new mountains being formed, and eventually errosion from rain would erode every protruding part of the earths surface until the surface was so flat the entire earth would be covered by water. Similar to what Europa looks like, a big ball of ice. Could that happen?