So, how exactly did the sea leave traces over almost all of the Earth’s landmass? Many areas previously occupied by the sea were eventually raised by powerful tectonic movements. Where this uplift occurred smoothly, plateaus and highlands were formed, and where there was a crushing of rocks into folds at the same time as the uplift, mountains grew. For example, many mountain systems in Eurasia — the Alps, the Caucasus, and the Himalayas — consist mostly of the former bottom of the extinct Tethys Ocean, the remnants of which are the Mediterranean, Black, and Caspian seas.

In addition, during warmer geological periods, when there were no glaciers on our planet, all the water that is now concentrated in the frozen masses was located in the World Ocean, resulting in an almost 230 ft increase in sea level. This means that many lowlands were flooded at that time.

So, almost any point of modern land was once home to a sea. Of course, there are places where there are no marine deposits — for example, virtually all of Finland. But this does not mean that the sea has never been there — it’s just that this country is near the center of a relatively recent glaciation, so the glacier has scraped off all traces of it.