The "Corsican geology" observation field
https://www.inaturalist.org/observation_fields/16686
Broad types of bedrock geology in Corsica, affecting overlying soil properties.
Definition and extents:
-
carbonate - limestones, dolostones, calcschists, marls, and other sedimentary rocks with a significant carbonate content, rarely metamorphosed (marble);
Caporalino—Omessa—Sant'Angelo and Pedani ridges, Punta di Calcina and Punta di u Furnellu summits, numerous smaller areas scattered from Belgodère to Venaco or from Cap Corse to Castagniccia and Fium'Orbo. -
siliciclastics - sandstones, conglomerates, shales, flysch, and other sedimentary rocks with minor or no carbonate content, sometimes metamorphosed (slate, paragneiss);
Saint-Florent and Bonifacio plateau, many parts of the Cap Corse, Castagniccia and Fium'Orbo areas, also from Balagne south to Corte and Vizzavona, very locally in the Falasorma—Porto area and on the Favone—Chiappa coast. -
granite - granitoids and associated intrusive magmatic rocks e.g. gabbro-diorite bodies, locally metamorphosed (orthogneiss);
dominant in two-thirds of the island west of a Saint-Florent—Corte—Solenzara line, plus few smaller areas in the Cap Corse, near Bastia, around Santa-Lucia-di-Mercurio and Linguizzeta. -
rhyolite - effusive silica-rich magmatic rocks, frequently with coeval pyroclastic deposits;
Monte Cinto range and its surroundings, Scandola peninsula, Falasorma valley, plus small areas near Morosaglia, Ghisoni, Vizzavona. -
ophiolite - magmatic series of oceanic-mantellic origin comprising peridotite, gabbros, basalts, frequently metamorphosed to serpentinites, metagabbros, blueschists etc.;
common in the eastern part of the island from Cap Corse to Solenzara through Castagniccia and Fium'Orbu, also in Balagna west of Ponte-Leccia ans around Corte. -
alluvium - surficial loose deposits masking underlying bedrock e.g. sand dunes, river gravel and silt, peat etc.;
coastal plains of Calvi, Ajaccio, Porto-Vecchio and from Bastia to Solenzara, in the deltas and valleys of major rivers, high-altitude peatlands.
N.B. Any geological variation of very limited extent is ignored, inasmuch as it has no discernible effect on soil formation or chemistry.
