So these people must have forayed with caution. It all has to do with events which took place long before any kind of human had appeared on the face of the earth. Imagine then, for millions of years, a mass of limestone is growing under the sea. This is happening around 200 million years ago. The continents look nothing like they do today.
Dinosaurs roam the land.
Slowly over millions of years the continents assume their present shape. As Africa barges into Europe, the land folds and forms mountain chains like the Alps. Other chunks are pushed out of their position. One piece is thrust westwards and comes to rest where Gibraltar is today. It is very different from the surrounding countryside which is made up of younger rocks.