This is a changing world. It changes from day to day, year to year, and from age to age. Rivers deepen their gorges as they carry more land to the sea. Mountains rise, only to be leveled gradually by winds and rain. Continents rise and sink into the sea. Such are the gradual changes of the physical earth as days add into years and years combine to become ages.
Stephen Jay Gould Hen's Teeth and Horse's Toes: Further Reflections in Natural History