Simplify the following text for a Grade 14 native English-speaking person.
Original: During cycles of global cooling , such as the most recent ice age , enough sea water became concentrated in the ice caps of the Arctic and Antarctica that the subsequent drop in eustatic sea levels exposed shallow sea floors that have subsequently re-flooded .
Simplified: During cycles of global cooling , such as the most recent ice age , enough sea water became concentrated in the ice caps of the Arctic and Antarctic that the subsequent drop in eustatic sea levels exposed shallow sea-floors that have subsequently re-flooded .