Many Lyonnais and tourists are familiar with the “Gros Caillou” located on the plateau of the Croix Rousse, in the 1st arrondissement of Lyon. Symbol of the district, it attracts curiosities and an important place in the culture and history of Lyon.

But in the Metropolis of Lyon, you can find another big rock, much less known.

A block laid here for more than 70 years

The “Gros pebble” of Croix-Rousse was discovered in 1861, while workers were carrying out work to pierce the funicular depending on the Presqu’île, in the center of Lyon, at Croix-Rousse.

That of Saint-Fons is located on the edge of the boulevard Yves Farge. This erratic block had to be excavated during works, such as that of Croix-Rousse, then moved and deposited there in February 1949, 73 years ago.

An inscription concerning its origin is carved directly into the stone. It reads “block of Cretaceous limestone probably originating from Savoy carried on this hill by the alpine glaciers in the first ages of Humanity”.

Similar origins

Origins shared with the “Gros pebble” of Croix-Rousse: the rock would also come from the Alps. Geology experts explain that it is a rock moved by the glacier which then covered the agglomeration, 140,000 years ago.

Both would come from the Maurienne and Tarentaise valleys, in the Alps, and would have traveled 200 kilometers, moved by the Riss glaciers.

The attentive eye will be able to find on the “big rock” of Saint-Fons the subtle trace left by a fossil shell tens of thousands of years ago, remarks Pierre Thomasprofessor at the Lyon geology laboratory.

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