The River Aulne in the autumn© Brittany Flyfishing

Brittany in the 6th century – abandoned, wet, cold and covered in forests

New research reveals a marked shift in the landscape of Northwestern France in Late Antiquity and the early Middle Ages

River Aulne © Brittany Flyfishing
River Aulne © Brittany Flyfishing/Philippe Dolivet.

During the period from ca. AD 300–600, early medieval Europe was on the cusp of a significant climatic shift. Marked by stormy weather and shifts in dynamic precipitation levels, the landscapes in Northwestern France changed. Likely caused by a mixture of cyclical variations in solar activities with shifts in the ocean and atmospheric activities, these changes were also reinforced by volcanic events in AD 536, 40, 74 and 626. Exactly which impact each of these explanatory factors contributed is still under debate. However, the deserted and reforested character of large stretches of Europe can no longer be questioned.

Recently, the same consequences were detected at the Bay of Brest in a study undertaken by a French group of scientists led by Claude Lambert, who has carried out a series of palynological studies at the Bay of Brest. The Bay is a shallow near-enclosed basin covering 180 km2 and surrounded by a 250 km long coastline. Two rivers – the Aulne and the Élorn – flow into the Bay.

According to the study, the cover of forests reached an absolute low of 40% during the Roman optimum c. 100 BC-AD 200. As opposed to this, a cover of 80-90% was reached between c. AD 300­–600. The cover consisted of oaks ad hazel mixed with alders and willow, while the pollen from cultivated grains virtually disappeared from the same area.

These results from Bretagne and the Bay of Brest reflect the results of the studies carried out in France in connection with the European programs such as Archaeomedes I and II as well as Archaedyn I and II. According to the data published by Laure Nuninger, both the number of settlements and the percentage of settled areas in different French regions showed significant growth during the Roman Optimum after the conquest of Caesar and until c. AD 250, after which a massive abandonment took place. Thus, in the southernmost region of Provence (Verdon), the settled area between c. 50 BC-AD 150 reached 22% of the area, falling rapidly over the next hundred years to 10%. The same deterioration has been documented concerning the number of settlements, which means the deterioration was not just a reflection of people moving into larger settlements or villages. Between AD 250 and AD 480, this new level was consolidated. However, following the establishment of the new successor kingdoms, the internecine wars between the Franks, the Visigoths, The Burgundians and the Ostrogoths, the rapid climate deterioration after the volcanic disasters in AD 536, 540 and later, and the devastation caused by the Justinian Plague, the region seems to have been virtually abandoned. This French region seems to have suffered the most. However, similar patterns can be detected allover France (and elsewhere).  Only the region around Tours presented a demographic growth pattern after AD 400-500, probably reflecting its role as a religious centre.

The new results from Bretagne corroborate these findings.

Although the cover of forest is is not as marked today, visitors to the region may experience som of the “old” landscape in the Parc naturel régional d’Armorique, which offers multiple historical as well as natural experiences.


The River Aulne. By kind permission from Brittany Flyfishing/Philippe Dolivet.


Striking forest revival at the end of the Roman Period in north‑western Europe
By C. Lambert, A. Penaud, M. Vidal, C. Gandini, L. Labeyrie, L. Chauvaud and A. Ehrhold
Scientific Reports. Nature (2020) Vol 10, Article number: 21984

Settlement patterns and territories over the long term from Prehistory to the Middle Ages
Laure Nuninger
In: NSF-ANR Workshop on Dynamics in the Human Sciences: Cognitive, Behavioral & Social Complexity, Reims : France (2009)




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