In the northeast of the Italian boot, not far from the Dolomites, a fortuitous mobile home breakdown led to a volcanic discovery: our friends Dominique and Jean-Michel had to park for a few days to repair, and discovered in the south of Venice, a isolated group of steep hills of volcanic origin:
The Euganean Hills (the Colli Euganei)
The Euganean Hills are a series of emergences of volcanic origin, which occupy an elliptical area of nearly 22,000 hectares.
The multiple aspects of these reliefs result from the meeting of the lava resulting from the fractures of the old ocean floor with the sedimentary rocks, which were raised and partially eroded.
First geological phase - sedimentary phase.
The oldest sedimentary rock is called Rosso ammonitico, it was formed between 150 and 135 million years ago, in the Upper Jurassic. This rock has many ammonite fossils from which it takes its name.
The next rock by genesis was formed between 135 and 90 million years ago, in the Lower Cretaceous, and is called Biancone. It is a white limestone composed almost entirely of calcareous shells of small microscopic organisms that have settled on the bottom of the open and deep sea.
Below we find the Scaglia Rossa, which dates back 90-55 million years, between the Upper Cretaceous and the Lower Eocene. It is a clayey limestone that often contains fossils like sea urchins and shark teeth (the sea temperature was around 25 ° C, like that of the tropics).
The last sedimentary rock formed is the Euganean Marne, 55 to 33 million years ago, from the Upper Eocene to the Lower Oligocene. It is a very clayey rock, greyish green in color, which is mainly found in the region of Teolo.
During this last sedimentary phase, about 43 million years ago, a first eruptive cycle took place.
To be continued ...
Sources: Gruppo Mineralogico Euganeo (GME), Collieuganei.it / geologia