Serravallian

The Serravallium is in the geologic timescale, the fourth stage of the Miocene ( Neogene ) and the upper stage of the Middle Miocene. She began geochronological before about 13.82 million years ago and ended about 11.62 million years and therefore lasted about 2.2 million years. The stage following the Langhium and is detached from the Tortonian.

Naming and history

The name of the step is derived from the village of Serravalle Scrivia province of Alessandria. The stage and the name was introduced by the Italian geologists Lorenzo Pareto, 1864.

Definition and GSSP

The lower boundary of the stage is defined by the first appearance of Nannofossil Type Sphenolithus heteromorphus. It is located within the magnetic polarity chronozone C5ABr. The upper limit is defined by the last subquadratus common occurrence of calcareous Nannofossil Type Discoaster kugleri and the planktonic foraminifera species Globigerinoides. The boundary is associated with the normal short - polar magnetic polarity Subchrone C5r.2n. The official type profile ( GSSP = " Global Stratotype Section and Point" ) is the Ras il - Pellegrin profile Fomm -Ir - Rih Bay on the west coast of Malta.