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Pietra serena

Introduction

The mountains in the Firenzuola area were created by uplift movements between 5 and 10 million years ago, which brought to the surface a sea bed which dates back to 20 million years ago. The alluvial deposits of the basin were thus the origin of the marly-sandstone outcrops that are often to be seen on the flanks of the mountains in the Alto Mugello, that is, strata of sandstone alternating with marl (also called galestro), which is limestone mixed with clay.

The widespread and clearly evident availability of this primary material explains the centuries-old tradition of stonemasons working with pietra serena, commonly called "Firenzuola stone", in the mountainous zone of the Alto Mugello. This area takes in the territory of the councils of Firenzuola, Palazzuolo sul Senio, and Marradi.

There are outcrops of the rock all along the lines cut by water courses, and it is clearly visible along the Santerno (Coniale), Senio (Acquadalto), and Lamone (Fantino) valleys; in the basin of the Rio Dell'Alpe towards the Rovigo valley; on the right-hand bank of the Torrente Sillaro between Piancaldoli and Giugnola, where the thinness of the surface capping above the stratified slabs makes extraction particularly convenient; in the area to the south-west of Palazzuolo sul Senio, in the whole series of small valleys cut by the tributaries of the Fosso di Campanara and the Fosso dell'Aghezzola; at Valcarpine, in the small valley of Fosso di Salecchio, to the east of Palazzuolo sul Senio; at Ca' del Gallo to the north-west of Marradi, between Ca' del Falco and Ca' del Vento.

This activity, which has extremely ancient roots, has never been abandoned, and indeed there are still today some 50 active quarries. 98% of the material extracted is sandstone, while the remaining 2% is colombino or alberese (fine limestone), which comes from an approximately 2.5 metre thick layer of resedimented sandstone; the latter is harder and more solid, and is recognisable by its darker colour, and by the presence of right-angled fractures which divide it into almost perfectly square blocks.

Translated by Jeremy Carden
Picture by Kee-Ho Casati


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