Earth has been around for roughly 4.6 billion years. Humans have been around for roughly 2 MILLION years. Since humans have been here you would think we would have learned more about our oceans, rivers and lakes but truth to the matter is we know squat. We barely know how water was formed here. Scientists have an array of theories but which theory is correct. Sort of like why did the Dinosaurs disappear? We can guess but we will probably never know the truth.