Ordovician glaciation

Category: Culture and Entertainment > Tourist Attraction

District: Aveiro > Arouca > Canelas e Espiunca > Gamarão de Cima

Location

The location of the Ordovician Glaciation is found in Gamarão de Cima, a serene area in the parish of Canelas and Espiunca, in the municipality of Arouca. Integrated into a predominantly natural landscape, this spot offers a unique perspective on the surrounding terrain, marked by rocky elevations characteristic of the region. Its position allows visitors to observe the geological configuration that testifies to Earth's history.

A Journey into Deep Time

In the heart of Arouca lies a place that narrates one of our planet's most dramatic stories: the Ordovician Glaciation. Around 445 million years ago, a global-scale event radically transformed the Earth. We are talking about the most intense glaciation on record since the appearance of complex organisms, a period so extreme that it led to the extinction of over 80% of the marine species of the time.

This icy phenomenon had its epicenter near what is now northwestern Africa, then situated at the South Pole. Its magnitude caused a sharp drop in ocean levels, leaving indelible marks on the geological configuration that we can observe today.

The Rocks That Tell the Story

After the coldest phase of the glaciation, approximately 444 million years ago, sands that were deposited at latitudes that were once close to the Antarctic pole gave rise to remarkable rock formations. This is the case of the quartzitic ridges, such as the Crista de Galinheiros, which stand out in the landscape, forming singular reliefs.

On these quartzitic formations, fine sediments of silts and clays were deposited, which today appear as light-toned schists. In these schists, visitors can search for and discover dropstones, rock fragments that were transported and released by the melting of icebergs that floated in the ancient Rheic Ocean. These "icy witnesses" are the visible proof of a remote past, where the thawing of gigantic ice masses left its mark.

The Toponym of Galinheiros

The imposing Crista de Galinheiros, which is part of this geosites, also carries a small local story. It is believed that its name "Galinheiros" may be linked to the abundance of moorhens that once populated the area. More than a mere designation, this ridge served, as early as the medieval period, as an important landmark and boundary for territories.

Documents dating back to 1153 attest to this historical importance, mentioning "Canelas, under the mountain Galliero," highlighting the role of the Crista de Galinheiros in the geography and administration of the Arouca region over the centuries.

License: https://creativecommons.org/licenses/by-sa/4.0/deed.pt