On Wed, 09 Aug 2006 12:04:48 GMT, "Roger Gelder"
>Following the earlier threads on sea-levels, I have Googled for possible
>estimates of dry land islands lying within the English Channel during the
>Roman and Saxon periods - say from 1 to 700 AD - but with no results apart
>from generalities on rises and drops in sea levels.
>Does anyone know of estimated islands (North Sea charts), now beneath the
>waves, which might have been dry land in this period?
The sea level rise after the last glaciation slowed to nearly zero
around 4000 BCE and has not changed more than a few centimeters since
2000 BCE. It is fair to say that tectonically controlled coastline
changes are more important than actual sea level changes. Some
megalithic graves in Britanny which were built close to the water are
now in the tidal flats. Ditto for The Wash, a tidal flat on the
eastern English coast. Some changes along the north Frisian coast of
Germany. The coastline history of the region from North Germany to
central Sweden is indeed quite complex because not only did the ocean
level rise, but also the land (post-glacial rebound).
But for the English Channel I am not aware of changes that are worth
mentioning, certainly there are no islands that vanished during the
period you mentioned.
The only island that did vanish, but much earlier than the time you
mentioned, was the Doggerbank before 6000 BCE. And the island of
Helgoland used to be much larger than today in medieval times. It is
getting smaller in part due to erosion, and in part due to the fact
that the island is tectonically sinking. It is on top of a salt dome
which was squeezed up during the ice age by the weight of the glaciers
to the east; that upsqueeze is still collapsing.