Gros Caillou (literally "big pebble") is a landmark of the French city of

Lyon Lyon,, ; Occitan language, Occitan: ''Lion'', hist. ''Lionés'' also spelled in English as Lyons, is the List of communes in France with over 20,000 inhabitants, third-largest city and Urban area (France), second-largest metropolitan area of F ...

in the neighborhood Croix-Rousse. The rock's mineralogical composition suggests it is a

glacial erratic A glacial erratic is glacially deposited rock differing from the type of rock native to the area in which it rests. Erratics, which take their name from the Latin word ' ("to wander"), are carried by glacial ice, often over distances of hundre ...

, and would have been transported from the nearby

Alps The Alps () ; german: Alpen ; it, Alpi ; rm, Alps ; sl, Alpe . are the highest and most extensive mountain range system that lies entirely in Europe, stretching approximately across seven Alpine countries (from west to east): France, Swi ...

by slowly moving glaciers.

Localization

Originally, Gros Caillou was located at the end of Boulevard de la Croix-Rousse, constructed in 1865, and the boundary between the 1st arrondissement (Croix-Rousse hill) and the 4th arrondissement (Croix-Rousse plateau). Until it was annexed in 1852, the Croix-Rousse Plateau was a separate city. Thus, the location of Gros Caillou at that intersection became a unifying symbol. At the beginning of the 21st century, an underground parking lot and green area took over this area and Gros Caillou was relocated 30m into the 1st arrondissement.

History

Gros Caillou is a

metamorphic Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causi ...

Triassic

quartzite Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tec ...

, typical of the alpine regions of Haute-

Maurienne Maurienne ( frp, Môrièna) is one of the provinces of Savoy, corresponding to the arrondissement of Saint-Jean-de-Maurienne in France. It is also the original name of the capital of the province, now Saint-Jean-de-Maurienne. Location The Mau ...

and Haute Tarentaise. It is rock that was displaced by glaciers over 200 km during the

Riss glaciation The Riss glaciation, Riss Glaciation, Riss ice age, Riss Ice Age, Riss glacial or Riss Glacial (german: Riß-Kaltzeit, ', ' or (obsolete) ') is the second youngest glaciation of the Pleistocene epoch in the traditional, quadripartite glacial classi ...

(around 140,000BC). The discovery of Gros Caillou dates back to 1861 during drilling of the tunnels of a funicular linking downtown Lyon to the Croix-Rousse plateau. The drilling had to be interrupted as the workers were blocked by an extremely hard rock, which they could not break.Source : After many attempts and work stoppages, Gros Caillou was eventually excavated, becoming a symbol of not only the annexation of Croix-Rousse, but a symbol of the perseverance of Lyon's inhabitants. Had the funicular not been under construction, Gros Caillou would never have been found and relocated to the east side of Croix-Rousse boulevard, where to this day it overlooks the

Rhône The Rhône ( , ; wae, Rotten ; frp, Rôno ; oc, Ròse ) is a major river in France and Switzerland, rising in the Alps and flowing west and south through Lake Geneva and southeastern France before discharging into the Mediterranean Sea. At Ar ...

River and the Alps.

Gallery

Lyon - Gros Caillou.jpg, The Gros Caillou at the beginning of the 20th century. Gros Caillou Lyon Croix-Rousse.JPG, Lyon gros caillou 073.JPG, The Gros Caillou from a different angle. File:Lyon (9 août 2013) 081.JPG, The Gros Caillou is a playground for local children. Lyon 04 - Vogue des Marrons - Place du Gros-Caillou (nuit).jpg, The Gros Caillou by night.

References

{{coord, 45.7747, N, 4.8352, E, source:wikidata, display=title Landmarks in France Buildings and structures in Lyon