Stadial
A stadial describes a cold phase (usually also the ice advance phase) within a glacial or interglacial and is often abbreviated in the specialist literature with the abbreviation GS .
The glacials and interglacials, which last around 100,000 years, never occur as a continuous, uninterrupted advance or retreat during an always equally cold or warm climatic period, but rather as periods with a long-term (100,000 years) average climate which, however, are climatically and also due to their geomorphological legacies can be further subdivided into colder (stadial) and warmer periods ( interstadial ).
Demarcation
The terms ice age / ice age , warm period / interglacial , cold period / glacial , stadial and interstadial are usually very misleading . All of these pairs of terms have different meanings and are not synonyms for each other.
Stadial and Glacial
Every glacial and interglacial was (with a naturally cold or warm climate ) characterized by smaller temperature fluctuations with slightly warmer and again slightly colder periods, each of which extended over several centuries to millennia. However, these relatively short-term climatic fluctuations (compared to the duration of the entire glacial under consideration) did not remain without effects on the relationship between snow accumulation and ablation of the inland ice sheet and glacier . As a reaction to the climatic fluctuations, there were phases of ice advancement (stadials) within a glacial and then again phases with increased ice melt, which moved the ice edge backwards (interstadials). An ice advancement phase with lower temperatures corresponds to a stadial, while a slightly warmer period, which leads to increased ablation, corresponds to an interstadial.
Corresponding to the dynamics of the ice as a landscape- shaping element caused by the change between stadial (ice advancement phases) and interstadial (ice retreat phases), the glacial geomorphological formation processes naturally also changed with the change between stadial and interstadial (e.g. accumulation of staggered terminal moraine walls , caused by sedimentation of a new terminal moraine after previous relocation of the ice edge in an interstadial).
Stadiale of the last glacial
The stadiums and interstadials of the last, youngest glacial ( Würm or Vistula glacial ) can best be reconstructed , as their geological traces were the last to emerge during the cold ages and are of course better preserved than the previous glaciations. Within the Würm / Weichsel glacial complex, numerous stadials and interstadials are distinguished, including the stadial of the older dryas , then the Allerød interstadial and finally the stadial of the younger dryas . After the Younger Dryas as the last stage of the Würm / Vistula glacial complex, the interglacial of the Holocene , in which we live today, began.
Subdivision
The spatial phenomena within the stationary or during a Stadials advancing Gletschereisrandlagen ( end moraine , kames and other deposition forms, glacial valleys and other meltwater channels) are considered as a stage referred to, in turn, in phases and scales are divided. the corresponding phenomena of the last ice age form, for example, striking landscape forms in the north German lowlands (Pomeranian, Frankfurt and Brandenburg stadiums). In southern Germany there are z. B. the Singen stage.
See also
literature
- Karl N. Thome: Introduction to the Quaternary. The age of the glaciers . Springer-Verlag, Berlin 1998 ( limited preview in the Google book search).
Individual evidence
- ↑ Brockhaus Encyclopedia, 19th ed., Vol. 19, p. 44 f.