Geology of the Etna Doc
How can geology influence the terroir of Etna
The previous article about“The Volcanic Ground of the Etna’s terroir” has introduced the idea of geology of the Etna Doc, with the geological map of Etna, depicting the perimeter defined by the Etna wines DOC consortium. This area includes many geological formations that represent the inorganic base of the different soils of Mount Etna.
For simplicity, here are all the various unities showed in the map in 5 macro-categories:
- Sandy sedimentary clays, with fine grain size and greyish colour;
- Lava fields of variable ages, characterized by an irregular surface, typical of the Etnean lava, and by an extremely variable colour, going from several grey shades to reddish-brown ones.
- Fall deposits (pyroclastic products) from explosive volcanic activity, more or less gross, often concentrated in the vicinity of the many lateral craters; these deposits are composed by scorias and lava pieces occasionally welded together, reddish in colour with grey-greenish thin ashes;
- Deposits composed mostly by very thin materials (volcanic ashes), melt together at high temperatures and characterized by a dark colour that, were particularly altered, often appears yellow.
- Rocks and deposits of materials fallen dating from ancient phases of Etna, when the volcanic activity was definitely more explosive (Pleistocene ignimbrite); these deposits are composed by pyroclasts of variable shape and size, welded together by a reddish thin sandy fabric
The volcanic ash on the vineyard
Finally, in this context, we cannot forget that Mount Etna is still one of the most active volcanoes in the world. Just consider that in the paroxysmal episode (particularly explosive eruptions) of December 2015, in just 3 days were erupted almost 14 million tons of new volcanic ashes, that were deposited to the ground.
This quantity is extremely variable from year to year but represents a support in terms of inorganic compounds that literally fell out of the sky that cannot be neglected. The following table shows the average chemical composition of Etna volcanic ashes.
It is immediately noticeable that besides the silica, main component of all volcanoes, iron, aluminium, and calcium compounds are the most widely represented.
Hence, it is easily understandable how in this geological and pedological context more unique than rare, however it is always remarkable the intense activity of man – particularly the agricultural one, that since the Roman times has affected the Etna area- it is impossible to prescind from the volcanic nature of the ground and its incredible shades, its geographical and temporal differences and consequently its never-ending transformations. Etna is notoriously the most studied volcano in the world, precisely for its fascinating complexity.
Investigating thoroughly the “geology” of Etna Doc wines could provide interesting information about what are the peculiarities of the vineyard, the longevity of the wine and even its intrinsic quality value.