Stephen Formation
The Stephen Formation is a geologic formation exposed in the Canadian Rockies of British Columbia and Alberta, on the western edge of the Western Canada Sedimentary Basin. It consists of shale, thin-bedded limestone, and siltstone that was deposited during Middle Cambrian time (513 to 497 million years ago). It is famous for the exceptional preservation of soft-bodied fossils: the Burgess Shale biota. The formation overlies the Cathedral escarpment, a submarine cliff; consequently it is divided into two quite separate parts, the 'thin' sequence deposited in the shallower waters atop the escarpment, and the 'thick' sequence deposited in the deeper waters beyond the cliff. Because the 'thick' Stephen Formation represents a distinct lithofacies, some authors suggest it warrants its own name, and dub it the Burgess Shale Formation. The stratigraphy of the Thin Stephen Formation has not been subject to extensive study, so except where explicitly mentioned this article applies mainly to the Thick Stephen Formation.
Q736917
geologic formation
Concept
Q1353201
Canadian Rockies
LOC
Q1974
British Columbia
LOC
Q1951
Alberta
LOC
Q2887579
Western Canada Sedimentary Basin
LOC
Q751300
shale
Concept
Q23757
limestone
Concept
Q565731
siltstone
Concept
Q1276038
Middle Cambrian
ORG
Q2122699
exceptional preservation
LOC
Q725856
Burgess Shale biota
UNK
Q65040221
Cathedral escarpment
Concept
Q7609209
Stephen Formation
LOC
Q7609209
Stephen Formation
LOC
Q7609209
Stephen Formation
LOC
Q7609209
Stephen Formation
LOC
+513^^http://www.w3.org/2001/XMLSchema#decimal
513
NUMBER
instance of
located in the administrative territorial entity
underlies
located in the administrative territorial entity
located in the administrative territorial entity
located in the administrative territorial entity