The Cambrian System has been traditionally subdivided into three series in Estonia.
Although the global stratotype section and point for the lower boundary of the Cambrian System was approved in 1992 (Brasier et al.
In December 2004, the International Subcommission on Cambrian Stratigraphy held a ballot on the subdivision of the Cambrian System and a fourfold subdivision was approved (Babcock et al.
Due to recent advances in international Cambrian stratigraphy the subdivision of the Cambrian System in Estonia should be discussed.
The lower boundary of the Cambrian System is formally defined at Fortune Head, Newfoundland, Canada, where it is marked a few metres above the base of the Treptichnus pedum Ichnozone (Gehling et al.
The position of the lower boundary of the second (unnamed) series of the Cambrian System is not yet fixed with a boundary stratotype, but the level will very likely be related to the appearance of trilobites.
The lower boundary of the third (unnamed) series of the Cambrian System will likely be tied to the first appearance of the trilobite Oryctocephalus indicus (Peng et al.
Changing perspectives on Cambrian chrono stratigraphy and progress toward subdivision of the Cambrian System.