ABSTRACT
The analysis of rounded well-worn pebbles, embedded in specimens of sedimentary rocks, reveals that the oceans have been in existence for at least 3 billion years. Over the intervening years, the topographical features of this planet, along with its oceans, have been changing continuously, although slowly relative to the human life span. Shorelines have distorted, continents have risen, fallen, and drifted apart, and the mean sea level has changed. The local and global weather systems, as well as the earth’s ecology, have been greatly influenced and modified by the presence of the oceans.
