Monday, May 23, 2011

The Mediterranean Coastline During the LGM

Last Glacial Maximum Coastline and Vegetation
map courtesy of the National Geophysical Data Center (Link here for legend)

The impact of glacial maximums are many and include dry and cold conditions.  However, their most obvious impact is that of sea level.  At the height of the LGM approximately 22kya, the worlds oceans were approximately 110 meters lower than they are today.  Even 10kya, the oceans were 40 meters lower than today.

It is interesting to consider the Mediterranean with a lower sea level.

As shown in the above map, Tunisia is connected or almost connected to the toe of Sicily.  Certainly, even 10kya, the crossing would be less than 40km and the opposing shoreline would be within view. 

The Aegean Sea would be smaller. 

Anatolia would be contiguous with Europe.

Cyprus would be less than 40km from the mainland of Anatolia.

The boot of Italy would be very closely connected to Othonoi.  This would connect Italy to Greece.

The Adriatic would be much smaller.  Northern Italy would be more directly connected to the Balkans.

Corsica and Sardinia would be connected and also closer to mainland Italy than today.

Ireland, England and France would be contiguous.

A glacier would separate Northern Italy from France.

I'm not sure about the Straight of Gibraltar. 
(Update (May 28th):  During the glacial maximums 20 kya and 150 kya, the Straight of Gibraltar was narrower, especially at the Camarinal Sill, (Link)

It would be great to see an underwater topological map of the Mediterranean, but so far, I haven't managed to locate one.  In any case, this does help to explain how, for instance, North Africans might have crossed into Italy or even Greece.  They didn't have to be ocean going seafarers to do so.  It also helps to explain the degree of genetic continuity between Greeks and Italians.

I thought I'd mention it, even though so far, I haven't managed to get that underwater topological map.

The Fleming et al paper which I reference in the previous post also shows that the sea level was at least 60 meters lower than today even 50kya, meaning that the Mediterranean coastline of today is an aberration.  With the exception of the last 10 thousand years, it has been relatively easy to cross from Tunisia to Sicily, from the heel of Italy to Greece, from Northern Italy to Corsica and Sardinia, from Anatolia to the Balkans and from Anatolia to Cyprus. 

Moreover, there was a period 150kya when these crossings would also have been more accessible than they are today.

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