The base of the Serravallian is at the first occurrence of fossils of the nanoplankton species Sphenolithus heteromorphus and is located in the chronozone C5ABr. The official Global Boundary Stratotype Section and Point (GSSP) for the Serravallian is in the 'Ras il-Pellegrin' section, located at the 'Ras il-Pellegrin' headland in the vicinity of 'Fomm ir-Rih' Bay, SW Malta.The base of the Serravallian is represented in the field as the formation boundary between the Globigerina Limestone formation and the Blue Clay formation. The base of the Serravallian is related to the Mi3b oxygen isotope excursion marking the onset of the Middle Miocene Cooling step.
The top of the Serravallian (the base of the Tortonian stage) is at the last common appearance of calcareous nannoplanktons Discoaster kugleri and planktonic foramGlobigerinoides subquadratus. It is also associated with the short normal-polarized chronozone C5r.2n.
^Krijgsman, W.; Garcés, M.; Langereis, C. G.; Daams, R.; Van Dam, J.; Van Der Meulen, A. J.; Agustí, J.; Cabrera, L. (1996). "A new chronology for the middle to late Miocene continental record in Spain". Earth and Planetary Science Letters. 142 (3-4): 367-380. Bibcode:1996E&PSL.142..367K. doi:10.1016/0012-821X(96)00109-4.