The Couches de Saint Christophe are a sedimentary formation deposited between the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

and the

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

. It is a very monotonous sequence of calcitic

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

s and black

schist Schist ( ) is a medium-grained metamorphic rock generally derived from fine-grained sedimentary rock, like shale. It shows pronounced ''schistosity'' (named for the rock). This means that the rock is composed of mineral grains easily seen with a l ...

s. These are interpreted as a

turbidite A turbidite is the geologic Deposition (geology), deposit of a turbidity current, which is a type of amalgamation of fluidal and sediment gravity flow responsible for distributing vast amounts of clastic sediment into the deep ocean. Sequencing ...

sequence. The average thickness of the unit is 500 m. The Couches de Saint Christophe are a post-rift sequence that overlies the Couches des Marmontains. The Couches de Saint Christophe occupy the following nappes: *

External Valais External may refer to: * Externality, in economics, the cost or benefit that affects a party who did not choose to incur that cost or benefit * Externals, a fictional group of X-Men antagonists See also * *Internal (disambiguation) Internal may ...

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 :* Petit St. Bernard unit *

Internal Valais Internal may refer to: *Internality as a concept in behavioural economics *Neijia, internal styles of Chinese martial arts *Neigong or "internal skills", a type of exercise in meditation associated with Daoism * ''Internal'' (album) by Safia, 2016 ...

:* Versoyen unit Large outcrops of the Couches de Saint Christophe crop out north 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 ...

. The type locality of the formation is the

Val de Bagnes Val de Bagnes, also called the Vallée de Bagnes (German: Bangital or Baniental) is a valley located in the Entremont District in the Canton of Valais of Switzerland. Geography Val de Bagnes is traversed by the Drance de Bagnes. In the upper ...

in the canton

Valais Valais ( , ; ), more formally, the Canton of Valais or Wallis, is one of the cantons of Switzerland, 26 cantons forming the Switzerland, Swiss Confederation. It is composed of thirteen districts and its capital and largest city is Sion, Switzer ...

Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

. It was first described by

Rudolf Trümpy Rudolf Trümpy (16 August 1921 – 30 January 2009) was a Swiss geologist, who was born in the small Swiss town of Glarus. He graduated from the ETH Zürich in the late 1940s with a thesis titled: “Der Lias der Glarner Alpen”. From 1947 to 1953 ...

in 1952. The formation is named after a chapel () to the northwest of

Verbier Verbier () is a village located in south-western Switzerland in the canton of Valais Valais ( , ; ), more formally, the Canton of Valais or Wallis, is one of the cantons of Switzerland, 26 cantons forming the Switzerland, Swiss Confederatio ...

. The Saint Christophe Formation can be correlated with the Sassauna Formation found in Graubünden and calcareous flysch found in the

Engadin The Engadin or Engadine (;This is the name in the two Romansh idioms that are spoken in the Engadin, Vallader and Puter, as well as in Sursilvan and Rumantsch Grischun. In Surmiran, the name is ''Nagiadegna'', and in Sutsilvan, it is ''Gidegna'' ...

References

{{Reflist Geologic formations of France Geologic formations of Switzerland Upper Cretaceous Series of Europe Cretaceous France Cretaceous Switzerland Cretaceous–Paleogene boundary Paleogene France Paleogene Switzerland Sandstone formations Geology of the Alps Schist formations