[47] It was not necessarily barbarous because metal weapons had not been invented.
The gradual sinking of the land and the process of coast erosion has greatly altered the geography of England. The beach on which Julius Cæsar landed has long since vanished, the dwellings of the ancient Azilian and Maglemosian colonists, who reached England in post-Glacial times, have been sunk below the English Channel. When Tilbury Docks were being excavated Roman remains were found embedded in clay several feet below high-water mark. Below several layers of peat and mud, and immediately under a bank of sand in which were fragments of decomposed wood, was found the human skeleton known as "Tilbury man". The land in this area was originally 80 feet above its present level.[48] But while England was sinking Scotland was rising. The MacArthur cave at Oban, in which Azilian hunters and fishermen made their home on the sea-beach, is now about 30 feet above the old sea-level.
Before Dover Strait had been widened by the gradual sinking of the land and the process of coast erosion, and before the great islands had vanished from the southern part of the North Sea, the early hunters and fishermen could have experienced no great difficulty in reaching England. It is possible that the Azilian, Tardenoisian, and Maglemosian peoples had made considerable progress in the art of navigation. Traces of the Tardenoisian industry have been obtained in Northern Egypt, along the ancient Libyan coast of North Africa where a great deal of land has been submerged, and especially at Tunis, and in Algiers, in Italy, and in England and Scotland, as has been noted. There were boats on the Mediterranean at a very early period. The island of Crete was reached long before the introduction of copper-working by seafarers who visited the island of Melos, and there obtained obsidian (natural glass) from which sharp implements were fashioned. Egyptian mariners, who dwelt on the Delta coast, imported cedar, not only from Lebanon but from Morocco, as has been found from the evidence afforded by mummies packed with the sawdust of cedar from the Atlas Mountains.[49] When this trade with Morocco began it is impossible to say with certainty. Long before 3000 B.C., however, the Egyptians were building boats that were fitted with masts and sails. The ancient mariners were active as explorers and traders before implements of copper came into use.