Calabrian is a subdivision of the PleistoceneEpoch of the geologic time scale, defined as 1.8 Ma—774,000 years ago ± 5,000 years, a period of ~.
The end of the stage is defined by the last magnetic pole reversal (781 ± 5 Ka) and plunge into an ice age and global drying possibly colder and drier than the late Miocene ( Messinian) through early Pliocene ( Zanclean) cold period. Originally the Calabrian was a European faunal stage primarily based on mollusk fossils. It has become the second geologic age in the Early Pleistocene. Many of the mammalian faunal assemblages of the Early Pleistocene start in the Gelasian. For example, the
Platygonus
''Platygonus'' ("flat head" in reference to the straight shape of the forehead) is an extinct genus of herbivorous peccaries of the family Tayassuidae, endemic to North and South America from the Miocene through Pleistocene epochs (10.3 million ...
and other
Blancan
The Blancan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 4,750,000 to 1,806,000 years BP, a period of .Mollusca (mollusks) and
Brachiopod
Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, wh ...
s to identify
stratigraphic
Stratigraphy is a branch of geology concerned with the study of rock layers ( strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks.
Stratigraphy has three related subfields: lithostra ...
boundaries. Thus the Calabrian was originally defined as an assemblage of mollusk fossils, most brachiopods being extinct by then. Efforts were then made to find the best representation of that assemblage in a stratigraphic section. By 1948 scientists used the initial appearance of cool-water (northern) invertebrate faunas in Mediterranean marine sediments as the beginning marker for the Calabrian. The 18th International Geological Congress in London (1948) placed the base of the Pleistocene at the base of the marine strata of the Calabrian Faunal Stage and denominated a
type section A stratotype or type section in geology is the physical location or outcrop of a particular reference exposure of a stratigraphic sequence or stratigraphic boundary. If the stratigraphic unit is layered, it is called a stratotype, whereas the stan ...
in southern Italy. However, it was discovered that the original type section was discontinuous at that point and that the base of the Calabrian Stage as defined by fauna assemblages extended to earlier levels within the Pleistocene. A new type section was chosen, several miles from the original one, at Vrica, 4 km south of
Crotone
Crotone (, ; nap, label= Crotonese, Cutrone or ) is a city and ''comune'' in Calabria, Italy. Founded as the Achaean colony of Kroton ( grc, Κρότων or ; la, Crotona) in Magna Graecia, it was known as Cotrone from the Middle Ages until ...
strontium
Strontium is the chemical element with the symbol Sr and atomic number 38. An alkaline earth metal, strontium is a soft silver-white yellowish metallic element that is highly chemically reactive. The metal forms a dark oxide layer when it is ex ...
and oxygenisotopes as well as of planktonic foraminifera has confirmed the viability of the current type section. The 27th International Geological Congress in Moscow in 1984 formally ratified the type section. The starting date was originally thought to be about 1.65 million years ago, but has been recalculated as 1.806 Mya.
Present formal definition
The Global Boundary Stratotype Section and Point, GSSP, for the former start of the Pleistocene is in a reference section at Vrica, 4 km south of Crotone in Calabria, Southern Italy, a location whose exact dating has recently been confirmed by analysis of strontium and oxygen isotopes as well as by planktonic foraminifera.Lourens, L., Hilgen, F., Shackleton, N.J., Laskar, J., Wilson, D., (2004) “The Neogene Period”. In: Gradstein, F., Ogg, J., Smith, A.G. (Eds.), Geologic Time Scale Cambridge University Press, Cambridge;
The beginning of the Calabrian hence is defined as: Just above top of magnetic polarity chronozone C2n (Olduvai) and the extinction level of calcareous nannofossil ''
Discoaster
''Discoaster'' is a genus of extinct star-shaped marine algae, with calcareous exoskeletons of between 5-40 μm across that are abundant as nanofossils in tropical deep-ocean deposits of Neogene age. ''Discoaster'' belongs to the haptophyte ...
brouweri'' (base Zone CN13). Above the boundary are the lowest occurrence of calcareous nannofossil medium ''
Gephyrocapsa
''Gephyrocapsa'' is a genus of haptophyte
The haptophytes, classified either as the Haptophyta, Haptophytina or Prymnesiophyta (named for ''Prymnesium''), are a clade of algae.
The names Haptophyceae or Prymnesiophyceae are sometimes used ins ...
spp.'' and the extinction level of the planktonic foraminifer ''
Globigerinoides
Globigerinoides is an extant genus of shallow-water planktonic foraminifera of family Globigerinidae. First appearing in the Oligocene these foraminifera are found in all modern oceans. Species of this genus occupy the euphotic zone, generally ...
Villafranchian
Villafranchian age ( ) is a period of geologic time (3.5–1.0 Ma) spanning the Late Pliocene and Early Pleistocene used more specifically with European Land Mammal Ages. Named by Italian geologist Lorenzo Pareto for a sequence of terrestrial se ...