Monferrato: the Story of a Sea That No Longer ExistsWalking through the hills and discovering that millions of years ago there was a sea here
By Simona Gotta - Monfreedom Guide There are places that tell their story through castles, churches, walls and historic buildings. Monferrato, however, also preserves a much older story, hidden beneath our feet.
During a hike, it can happen that you walk through vineyards, follow a white country road or stop in front of a pale rocky outcrop and suddenly notice a fossilized shell. At that moment, the landscape changes completely, because that shell reminds us of something that today seems almost impossible to imagine: where we now see hills, vineyards, farmhouses and small villages, millions of years ago there was a sea.
It is one of the stories I most enjoy telling while guiding people along the trails of Monferrato.
Because we are not simply looking at a beautiful hilly landscape. We are literally walking on the floor of ancient seas.
A Monferrato very different from the one we know today
To imagine it, we need to forget for a moment everything we see around us. No vineyards, no bell towers on the ridges and, of course, no villages.
Between roughly 20 and 14 million years ago, during the Miocene, an important part of the Casalese Monferrato area was covered by marine environments. The landscape changed continuously because of geological movements connected with the formation of the Alps and, above all, the Apennines. Some areas emerged like islands, while others were submerged again.
At certain times, relatively shallow marine environments developed under climatic conditions warmer than those of today. Those waters were inhabited by molluscs, sea urchins, corals, brachiopods, barnacles, bryozoans, calcareous algae and countless microscopic organisms. Later, the sea became deeper and new sediments accumulated on the seabed.
Millions of years later, those sediments became the rocks that today form part of these hills.
Pietra da Cantoni is a page from that ancient sea
One of the most fascinating witnesses of this history is the Pietra da Cantoni, particularly characteristic of the Casalese Monferrato area.
It is a sedimentary rock of marine origin, formed mainly between about 20 and 14 million years ago. Inside it, traces and remains of the organisms that lived in those ancient waters were preserved: molluscs, calcareous red algae, sea urchins, foraminifera and many other small marine organisms. Even shark teeth and remains have been found.
Thinking about this while walking through the countryside has a particular effect.
The same stone that today forms walls, houses, cellars and Infernot was created by sediments that accumulated on the seabed. So when we touch a wall made of Pietra da Cantoni, we are touching a material whose story began millions of years before humans appeared.
This is also why I do not like describing these hills simply as “gentle” or “scenic”. They are certainly beautiful, but beneath that beauty lies an extraordinary geological complexity.
Shells among the vineyards: when fossils appear along the trail
One of the most rewarding experiences during a hike is finding a fossil directly in a natural rock outcrop.
It does not necessarily mean discovering a spectacular museum-quality specimen. More often, we see shell impressions, fragments of shells, small fossils embedded in the rock or particular structures that reveal the marine origin of the sediments.
These are details that can easily go unnoticed if you do not know what to look for.
This is where the role of a guide becomes especially interesting. A rock face that may initially seem completely ordinary can contain an astonishing amount of information, and after just a few minutes of explanation people begin to observe the rocks with completely different eyes.
From that moment on, they no longer walk while looking only at the landscape ahead. They begin to look beneath their feet as well.
Rosignano Monferrato: one of the best places to discover traces of the ancient sea
If we want to tell this story while walking, Rosignano Monferrato is one of the most interesting areas.
Here, a geological route has been created around the theme of the ancient tropical seas of the Pietra da Cantoni. It includes several stops spread across the main village and surrounding areas such as Valle Ghenza, Stevani, San Martino, Berroni, Colma and the old quarry area near Uviglie.
The route makes it possible to observe different geological formations and understand how the landscape we see today is the result of millions of years of transformation.
The hamlet of Colma is particularly interesting, where fossil remains of rhodoliths can still be observed. These are structures formed by calcareous red algae that lived in the ancient marine environments of Monferrato.
Here the connection between what we explain and what can actually be seen becomes immediate.
We do not need to imagine that ancient sea only through a reconstruction or a drawing. We can see real evidence of it in the rock.
Cella Monte: walking inside geology
Another place that is almost essential when talking about the lost sea of Monferrato is Cella Monte.
Here, Pietra da Cantoni is everywhere: in houses, historic buildings, old quarries and, of course, in the Infernot carved beneath the village.
The area also offers a geological walking route that passes through the historic centre, Regione Sardegna and the hamlet of Coppi. It was created precisely to explain the geology, biodiversity and transformations of the ancient seas of Monferrato. The route also connects geological history with vineyards, quarrying activities and even the local truffle tradition.
In Cella Monte we can therefore do something I find especially fascinating: walk on marine rock, observe buildings constructed from that same material and finally descend inside it by entering the Infernot.
It is difficult to find a more immediate way to understand how deeply geology has influenced the lives of the people of Monferrato.
The local Ecomuseum of Pietra da Cantoni also preserves fossils and educational materials that help explain the different geological phases experienced by these hills.
Between Rosignano, Cella Monte, Ozzano, Ottiglio and Vignale, marine rocks appear again and again
The presence of Pietra da Cantoni and other marine sediments is not limited to one village.
Rock outcrops and old quarries can be found across a broad area of Casalese Monferrato, including Cella Monte, Rosignano Monferrato, Ozzano Monferrato, Ottiglio, Moleto and Vignale Monferrato.
These are some of the places where, while walking along dirt roads, natural cuttings or former quarry areas, it is easier to observe rocks that preserve evidence of the ancient marine environment.
In Vignale, for example, Pietra da Cantoni forms part of the geological base on which the village stands, while nearby other marine formations also appear, including the fossil-rich marls known as the Marne di Sant’Agata Fossili.
For hikers, the extraordinary thing is precisely this: geology is not confined inside a museum. It appears along roads, in the walls of houses, on hillsides and beside trails, continuing to tell its story wherever we know how to recognize it.
Sea urchins and even sharks in Monferrato
Among the fossils found in Pietra da Cantoni, some are particularly surprising.
One example is Schizaster ozzanensis, a fossil sea urchin whose name itself recalls Ozzano Monferrato.
The rocks have also preserved remains of fish and sharks, including teeth belonging to large marine species.
This is one of those details I love telling during a hike because it immediately creates an almost cinematic image: where today we walk peacefully among vineyards of Barbera and Grignolino, millions of years ago fish and sharks were swimming.
Of course, we should not imagine the present-day landscape simply covered by water. Over millions of years, everything changed: the position of the land, the depth of the sea, the climate, the fauna and the shape of the territory itself.
And that is precisely what makes the story so fascinating.
When the sea began to disappear
From around 7 to 5 million years ago, marine sediments gradually began to deform and emerge. Uplift and tectonic movements contributed to the formation of the hills, while rivers and erosion slowly began to shape the landscape.
By around 3.5 million years ago, the sea had permanently retreated from this part of Piedmont.
From then on, water, wind, climate changes and rivers continued to sculpt the land until they created the soft hills that today we immediately associate with Monferrato.
Humans arrived much later.
They cleared some slopes, cultivated the most suitable areas, planted vineyards, opened quarries, built houses with local stone and carved out the Infernot.
The landscape we see today is therefore the result of two overlapping stories: a natural one, millions of years old, and a much more recent human one.
Do not collect them: observing fossils is far more interesting
When we find fossils during a hike, the temptation to pick them up can be strong. However, it is much better to leave them where they are, especially when they are embedded directly in the rock.
Once removed from their geological context, fossils lose part of their scientific meaning. Their position within the rock, the type of sediment and the other fossils found in the same layer can provide valuable information about the environment in which the organism once lived.
For this reason, I prefer to photograph them, observe them and use them to tell the story of the place.
After all, the real fascination does not lie in taking a fossil shell home.
It lies in looking at it and imagining the sea that existed here millions of years ago.
Monferrato becomes even more surprising when we learn to look beneath the vineyards
This is one of the aspects I most enjoy sharing during Monfreedom excursions.
In front of us we see cultivated hills, villages on the ridges, castles, vineyards and, on clear days, even the Alps in the distance. Yet beneath all of this lies another landscape, invisible and incredibly ancient.
It is the landscape of the sea.
A warm sea populated by molluscs, sea urchins, algae, fish and sharks, which disappeared millions of years ago but is still present in the rocks, fossils, Pietra da Cantoni and even in the buildings constructed by people.
So the next time you walk through Rosignano, Cella Monte, Ozzano, Ottiglio, Moleto or Vignale, try not to look only towards the horizon.
Look at a rock face, an old stone wall, the edge of a dirt road or an outcrop beside the trail.
You may find yourself looking at a shell.
And that small shell may be millions of years old, telling the story of a sea that no longer exists.
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