A lunar landscape with subterranean labyrinths.
The Marguareis Nature Park in the upper Pesio and Tanaro valleys surrounds and embraces the mountain massif of Marguareis in the heart of the Ligurian Alps . The Ligurian Alps are the sub-sector of the Maritime Alps that stretches from the Colle di Cadibona to the Colle di Tenda. Their rocks were formed by the sediments deposited on the bottom of a warm sea 200 million years ago. Layer after layer, the grey limestone rocks we walk on today, emerged 38 million years ago. Once exposed to the air and light, the ancient seabed became a plateau and was shaped by water and the elements over millennia. Water dissolves the calcium carbonate in limestone, eroding it, cutting right through it in places. The cracks in the rock have thus become tunnels, sink holes, grand halls the size of football pitches: in the caves, the roots of the sky have formed.
The Marguareis massif, the heart of the Park, is one of the most striking examples of high-altitude karst in Italy and in Europe. Both the glacial forms (the result of modeling by ancient glaciers) and the karst forms (derived from the action of water on the limestone rocks) are in a particular context: the absence of vegetation makes these mountains an open air geology book, where you can admire the patient "game" played over millions of years by rock, water and time.
The current superficial morphology, what we call the base of the "landscape", is the result of a drama in three acts: the formation of karst surfaces (I act), erosion by glaciers in the last ice age (II act), subsequent karst erosion of the glaciated forms (act III).
From the speleological point of view, the Ligurian Alps is an underground world that still hides many secrets. The Piaggiabella complex, with extending over 43 km and almost 1 km deep, is the main cavity of the system: it comes close without connecting to the Labassa cave (15 km and over 500 m deep): finding a passage between the two "dames" of Marguareis is the dream of every pot-holer from Liguria and Piedmont. Around the Colle dei Signori, there are over 60 square kilometres of karst territory and many kilometres of natural underground tunnels.
Geotour del Marguareis
Un viaggio lungo 300 milioni di anni nella storia della Terra nell'itinerario autoguidato realizzato dal Dipartimento di Scienze della Terra dell’Università e dal CNR-IGG di Torino.
Massiccio sedimentario del Marguareis
Sedimento su sedimento, nel corso di milioni di anni, si sono formati il Massiccio del Marguareis - un altopiano di roccia calcarea permeabile all’acqua - e il basamento impermeabile su cui poggia.