Jigsaw puzzle: a thousand-piece geological map of France!

It is punctuated by numerous events: volcanic eruptions, mountain formation, erosion and weathering, sediment deposition, climate change, sea level fluctuations, the emergence of species, major biological crises, falling asteroids, and many more.

To help the public better understand the geological history of France, we are offering a version derived from the geological reference map. With specially designed visuals and a geological cross-section stretching from Calvados to the Alsace plain, this new 68 x 49 cm jigsaw puzzle, made up of 1,000 pieces, is a fun way to see how the subsurface is structured in three dimensions.

The old basement foundation

The oldest rocks in France are around two billion years old. Intermittent outcrops can be found along a line running from the north of Brittany to the north of the Cotentin peninsula, passing through the Channel Islands.

The next oldest rocks have been dated at between 600 and 250 million years ago. These rocks can be seen in the ancient massifs that form the basement foundation or bedrock, including: The Armorican Massif, the Massif Central, the centre of the Pyrenees, the western part of Corsica, the Maures Massif, parts of the Alps, Vosges and Ardennes.

These rocks are also found elsewhere, but at greater depths. This is clearly illustrated by the geological cross-section.

They are mainly represented in warm hues (red, orange, pink), colours that have traditionally been used to evoke the intense heat of the original magmas, and dark hues (brown, green and grey) to illustrate ancient sedimentary rocks that have been more or less transformed.

The major sedimentary basins

The major sedimentary basins lie on the ancient bedrock. They are found in Aquitaine, and in the northern half of the country, in an area delimited by Caen, Poitiers and Strasbourg, extending north towards England. These basins are tinted with the same succession of mauve, blue, green, orange and yellow.

The cross-section of the Paris Basin clearly shows the stacking of the main sedimentary subdivisions, which are around 3,000 metres thick in the vicinity of Paris.

The south-eastern basin has the same series of colours, but in a more disordered fashion due to the tectonic upheavals that created the Pyrenees and the Alps. In these young mountains the ancient bedrock also reappears here and there.

And then...

Following the compression that produced the young mountain ranges, the Earth's crust stretched, creating the collapse trenches in the Massif Central (Limagnes and Forez plain), on the Saône-Rhône axis (Dombes and Bresse) and in the Alsace plain. They are shown in light colours on the map.

Volcanic rocks, on the other hand, are shown in dark mauve. They are found mainly in the heart of the Massif Central, including the Cantal massif, Europe's largest volcano with a diameter of 60 km. Auvergne is also home to France's youngest volcano (around 5000 BCE), now filled by Lake Pavin.

Unique traces of an asteroid impact in France

In the Limousin region, rocks known as impactites have been found over an area with a diameter of around twenty kilometres. They result from the impact of an asteroid about 1.5 km in diameter (weighing 6 billion tonnes!) that arrived at a speed of 20 km/s 207 million years ago (Triassic period). This deformed the rocks to a depth of over 5 kilometres. That is almost twice the height of the thick part of the Paris Basin shown on the cross-section.

This new jigsaw puzzle will make a great gift, or a treat for yourself. An entertaining way of discovering and appreciating the rich geological diversity of our beautiful country. See for yourself!