The Brèches du Grand Fond Group is a

group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic iden ...

of stratigraphic formations in France that were deposited between the

Middle Jurassic The Middle Jurassic is the second Epoch (geology), epoch of the Jurassic Period (geology), Period. It lasted from about 174.1 to 161.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relativel ...

and the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

. The deposition was contemporaneous to the rifting of the

Valais ocean The Valais Ocean is a subducted oceanic basin which was situated between the continent Europe and the microcontinent Iberia or so called Briançonnais microcontinent. Remnants of the Valais ocean are found in the western Alps and in tectonic win ...

, and overlies the pre-rift rocks along an

angular unconformity An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval ...

. The Brèches du Grand Fond Group is overlain by the post-rift sequences Couches de l’Aroley, Couches des Marmontains and the Couches de Saint Christophe. The Brèches du Grand Fond Group consists of two formations that are found in the External Valais units, the younger Pyramides Calcaires Formation and the older Dent d'Arpire Formation. The deposition of these two units was roughly contemporaneous to the deposition of the Brèches du Collet des Rousses and the Complexe Antéflysch Formation of the Internal Valais units. In general the Brèches du Grand Fond Group consists of coarse grained clastic sediments composed of pre-rift lithologies. Outcrops can be studied The Brèches du Grand Fond Group can be found within the following nappes: * External Valais :*

Moûtiers unit Moûtiers (; Arpitan: ''Motiérs''), historically also called Tarentaise, is a commune in the Savoie department in the Auvergne-Rhône-Alpes region in Southeastern France. Moûtiers is the main access point to the Les Trois Vallées ski region ...

:* Roc de l'Enfer unit Outcrops occur to the northwest of

Bourg-Saint-Maurice Bourg-Saint-Maurice (; Arpitan: ''Bôrg-Sant-Mori'' or simply ''Le Bôrg''), popularly known as Bourg, is a commune in the Savoie department in the Auvergne-Rhône-Alpes region in south-eastern France. Located on the Italian border south of Cha ...

References

{{DEFAULTSORT:Breches du Grand Fond Group Geologic groups of Europe Geologic formations of France Geology of the Alps