Settlement & Ports
When we look at old maps of Roman settlements and ports around Britain and the Mediterranean, we see that a majority are built on the coastline or waterways of these countries. This fact is not surprising as these locations would need constant supply of goods for trading and construction. However, if we look more closely at these at these sites, it becomes apparent that some of the locations are far away from the shoreline or rivers that once supplied them. For example, Brading Roman Villa in the Isle of Wight 1. 5km from the sea and 500m from the nearest in water river, which is so small that it could hardly take a canoe let alone a Roman supply ship.
Another example is in Turkey in the Roman capital of Asia Minor, Ephesus where Queen Cleopatra sailed from Egypt to the Roman high command to meet Anthony, with a ceremony that is still enacted today for the tourists. Ephasis is a good 8km from the sea, so unless Queen Cleopatra was in need of a long walk, the shoreline has drastically changed since Roman times. The final and best example is Lewes in East Sussex, which is an incredible 15km from the coast. Moreover, this vast distance from the sea we see today is compounded by the fact that sea levels have risen by 2m over the last two thousand years, showing that the natural distance from these harbours to the coastline was even greater during the past.
The history books will tell you that this is down to either natural or manmade drainage, but why would you wish to allow a thriving harbour to silt up if it was commercially viable?
In all three cases, this silting resulted in the houses or cities being completely abandoned or livelihoods lost, and the towns scaled down as a consequence. However, what is remarkable about all these locations is that they share in common factor and that the harbours were directly fed by rivers emptying into that area.
These locations we built, in a time when the groundwaters were high, and the river flow was sufficient to flood the harbour allowing boats to sail in and out of the location. This rise in groundwater was due to the 'Post Glacial Flooding' which occurred directly after the last Ice Age and has been constantly reducing in size affecting rivers all over Europe for the past 12,000 years. This is because the surplus water drains into the sea raising sea levels (that's why sea levels over the past five years have risen although global warming has 'plateaued' and the Antarctic ice sheets increased in size) and cannot be replaced by the small amount of rain water that tops up the groundwater in certain seasons.
The loss of this groundwater has been compounded over the last 1000 years as agriculture and the massive increase in populations have demanded we use more of this precious groundwater for drinking and manufacture processes and hence the loss of rivers and streams in hot summers. Moreover, this water will only be fully replenished when the next ice age covers Europe once again, so until then, this loss of groundwater we see affecting the shorelines of these ancient fortifications, and harbours will continue until the sea rise eventually floods the same area again, but not with freshwater this time, but with sea water.