According to Moti, geologic processes through the ages have resulted in the following soils distribution:
- Alluvial sediments and debris along major river valleys
- Gravels, sands, and clays deposited during the Pliocene and early Pleistocene
- Marly deposits during the Oligocene - Miocene
- Stratigraphic Umbria-Marche deposits from the Jurassic-Miocene
- In the southwest, volcanic deposits from the eruptions of the Vulsino volcano.
|Schematic geologic map of Umbria. |
Blue = Limestone; Gold = Sandstone rocks;
Yellow = Inter-mountain basins; and
Purple = Volcanic complexes (Source:
Andrea Moti, researchgate.net)
Orvieto, one of the three major Umbrian wine regions, is centered around the town of Orvieto in southwest Umbria which, itself, sits on the northern edge of a broad volcanic plateau (alfina) which originated in the Quaternary period. Orvieto is shown in the map below.
Over time, the River Paglia and its tributaries cut the volcanic tuff of the Alfina Plateau into mesas (Bardano and Orvieto, for example) or buttes (Rocca Ripensa, for example). The distribution of soils in the Orvieto area is shown in the figure below. Note that the main difference between this distribution and the broader Umbrian distribution is the addition of a volcanic layer to the series.
In mesas, there is a thin layer of volcanic origin from a fluvial-lacustrine environment that is called the Albornoz series. This soil type is probably incorporated into the topmost layers in non-mesa, non-butte structures.
The topmost stratigraphic layer in mesas, and a significant component of the recent alluvial sediments, is the effluvia of the Vulsino eruptions which occurred over a 300,000-year period. This lithoidal tuff with black scoriae includes "yellow-orange tuff of lithoidal texture with numerous inclusions of pumice and extremely friable rock of a grey color that incorrectly takes the name of pozzolano." Both the pozzolano and tuff have natural porosity.
Andrea Moti, An Example of Possible Application of Detailed Geological Maps. The 11 DOC/DOCG Destined to Wine Production in Umbria, researchgate.net
Corrado Cencetti, et al., The Rock of Orvieto (Umbria, Central Italy), researchgate.net
Mario Menichetti and Rodolfo Coccione, Umbria - Marche Apennine geological field trip, researchgate.net
Livio Vezzani, et al., Geology and Tectonic Evolution of the Central-Southern Apennines, Italy
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