Elsterian glacial period dating
Deposits associated with the Don Glaciation include lodgement and ablation tills, as well as a series of glacio-lacustrine sediments.Within the tills granites (about 60%) dominate the boulder fraction.Of these, only the Gelasian and Calabrian are formal intervals, whereas others await ratification by the ICS.The Calabrian, which was previously known as the early Pleistocene, extends to the Brunhes–Matuyama paleomagnetic boundary at 780,000 years ago.
Other criteria that have been used to define the Pliocene–Pleistocene include the appearance of humans, the appearance of certain vertebrate fossils in Europe, and the appearance or extinction of certain microfossils in deep-sea sediments.
However, recently Stephan (1995) suggested that a glacial tunnel valley at Leck in north-west Schleswig-Holstein may contain interglacial deposits of Harreskovian age. (1966) and Grüger (1968) described an interglacial deposit, stratified between a lower, weathered and an upper fresher till, both containing erratics of Scandinavian origin.
Pollen analysis suggested that this belonged to the Pre-and Early temperate zones of a temperate Stage that was certainly not the Holsteinian or Domnitzian, and which they then believed was not Eemian either.
(Changes in loess grain size suggest regional climate changes.) After years of discussion, the International Union of Geological Sciences (IUGS) and the International Commission on Stratigraphy (ICS) designated the Gelasian as the lowermost stage of the Pleistocene Epoch.
The Pleistocene is subdivided into four ages and their corresponding rock units: the Gelasian (2.6 million to 1.8 million years ago), the Calabrian (1.8 million to 780,000 years ago), the Ionian (780,000 to 126,000 years ago), and the Tarantian (126,000 to 11,700 years ago).
These criteria continue to be considered locally, and some workers advocate a climatic boundary at about 2.4 million years.