Flo ( sv, Flo socken) is a historic parish (''socken'') in the Swedish province of

Västergötland Västergötland (), also known as West Gothland or the Latinized version Westrogothia in older literature, is one of the 25 traditional non-administrative provinces of Sweden (''landskap'' in Swedish), situated in the southwest of Sweden. Vä ...

. Since 1971 it has been a part of

Grästorp Municipality Grästorp Municipality (''Grästorps kommun'') is a municipality in Västra Götaland County in western Sweden. Its seat is located in the town of Grästorp. Grästorp Municipality is located right in the middle of Västra Götaland County, by ...

Geology

Flo parish is the namesake for the

Floian The Floian is the second stage of the Ordovician Period. It succeeds the Tremadocian with which it forms the Lower Ordovician epoch. It precedes the Dapingian Stage of the Middle Ordovician. The Floian extended from to million years ago. The ...

stage, which is the second stage of the

Lower Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. T ...

. The base of the

is defined at the Diabasbrottet quarry type section (

GSSP A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. The effort to define GSSPs is conducted ...

) 5 km to the northwest of Flo. The base is defined in the quarry as the lowest stratigraphic occurrence of the

graptolite Graptolites are a group of colonial animals, members of the subclass Graptolithina within the class Pterobranchia. These filter-feeding organisms are known chiefly from fossils found from the Middle Cambrian (Miaolingian, Wuliuan) through the L ...

species ''

Tetragraptus approximatus ''Tetragraptus approximatus'' is a species of dichograptid graptolite belonging to the genus ''Tetragraptus''. It existed during the Floian Age ( million years ago) of the Ordovician. It is an important index fossil in biostratigraphy. Descript ...

''.

References

{{Authority control Populated places in Västra Götaland County