Along the Voie Verte downhill from Caen, after Etavaux, you enter the Armorican Massif, made up of ancient rocks, those also found in Suisse Normande.
At this precise spot, the Orne has uncovered a series of rectified rocks, a trace of an ancient folded mountain chain: this is what is known as the syncline, a geological ensemble that resembles a thousand sheets of rock that appear like leaves on the edge of a book.
In the area of May sur Orne, this structure is all the more evident as many traces of exploitation have left visible rocks: iron mines, paving stone quarries, marble quarries..
The most prestigious site is the Laize quarry (May/Orne), where you can see the rocks from before the syncline below (the schists found in the Boucle du Hom for example), the rectified rocks of the syncline and the rocks above: the limestones of the Caen plain, which belong to another geological group: the Parisian Basin
Over the few kilometres between the Laize quarry in the south and Feuguerolles-Bully in the north, one will have come across marble, conglomerates, sandstones of various kinds, shales, iron ore, travertine, ampelites... more than 600 million years of earth's history can be read there, summing up almost entirely the geological history of the region.