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E - 201: Surfing the African Plate for Extra Barley Yield - the Geology of Magna Graecia

Updated: Apr 16, 2021

Was trying to find farm yield information for Sicily and Southern Italy all day yesterday but felt I was looking for the famous needle in the haystack. The information I was looking for does not seem to exist. Peter Garnsey from the University of Cambridge perfectly summarized it: “The ancients were uninterested in assembling the data we require. Worse still, they lacked key economic concepts like productivity…”

Barley with its typical long ears

Not going to pursue this avenue for a while and hope serendipity will intervene at one point! Both Sicily and Southern Italy must have been very fertile though. Otherwise the Greek colonists would not have crossed the Ionian Sea and settled there. Coming from a land where only 10% of land was arable, they recognized fertile land when they saw it. What made these lands so fertile? On which type of soil does barley grow well? 90% of the Greek grain production was barley.

Optimal pH for Barley (and most other plants)

Remember pH values from High School – with acidic values from 0 – 7 and alkaline from 7 – 14? Most of Greece and Italy’s Apennine are folded sea floor sediments from the Tethys Ocean between Africa and Europe which closed 20 million years ago. Sediments are most often alkaline since they are formed from deposited limestone (calcium). Alkaline soil is not ideal for cultivating barley which does best on slightly acidic soil with a pH from 6.0 to 6.5.

The Mediterranean in the Late Miocene about 8 million years ago

Sicily and Southern Italy have a different geological history than the Apennine Peninsula. They both are part of the old African plate and consist of different material. Their rocks are mostly crystalline and slightly acidic. Ideal places for growing barley! Was surprised myself to see how complex the geology of Southern Italy is. The collision of the European and African plate was not only frontal but also lateral. Apulia, the heel of Italy, is a splinter of the old African plate. Calabria consists of African rocks which were folded near today’s Spain and Sicily has in addition its Etna volcano with its basalt rocks. All rich in minerals!

Sicily's and Southern Italy's complex geological set-up

How this was all created is best understood by watching one of the animated clips on plate tectonics you find on the internet. There is one additional element which I have not mentioned yet. All plants like soil with feldspar and granite crystals. The coastal plains are deposits resulting from 20 million years of erosion and full of it. Rivers created wide, fan like features which extend far into the Ionian sea and eventually joined to form the fertile coastal plains. These plains also drain perfectly well and provide perfect farming soil.

The spectacular journey of Calabria – the graph above shows its position 20 million years ago (1), 10 m (2) , 5 m (3) and today

Over time, the continued erosion of Calabria’s mountains pushed the coast lines further out. Many of the Greek colonies we are going to visit are now about 1 km away from the shore, their harbors long silted. The predominant sea current from west to east also formed the long sand beaches which tourist love so much. There will be few people like us walking through ancient ruins - most of the holiday makers do not venture beyond the beach chair with their towel prepositioned at 6 am.

Did the Greek colonist have any idea of the complex geology they set foot on when they arrived in the 8th century BC? Of course not. For them it was all destiny and the Gods that brought them to these fertile shores. The numbers of magnificent temples they built for the goddess Demeter and her daughter Persephone speak volumes – but as promised, this will be part of a later blog!

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