Eridanus (geology)
| system | series | step | ≈ age ( mya ) |
|---|---|---|---|
| higher | higher | higher | younger |
| Paleogene | Oligocene | Chattium | 23.03 ⬍ 28.1 |
| Rupelium | 28.1 ⬍ 33.9 |
||
| Eocene | Priobonium | 33.9 ⬍ 38 |
|
| Bartonium | 38 ⬍ 41.3 |
||
| lutetium | 41.3 ⬍ 47.8 |
||
| Ypresium | 47.8 ⬍ 56 |
||
| Paleocene | Thanetium | 56 ⬍ 59.2 |
|
| Seelandium | 59.2 ⬍ 61.6 |
||
| Danium | 61.6 ⬍ 66 |
||
| deeper | deeper | deeper | older |
The Eridanos (Baltic Main Stream) is a river that flowed through today's Baltic Sea region in the Eocene . The Pleistocene glaciation later reshaped the region, the Baltic Sea basin was excavated and the waters that originally fed the river now flow into the Baltic Sea.
Origin of name
The name goes back to the river Eridanos in Greek mythology. It can be detected geologically through deposits and the deep relief of the Baltic Sea basin. Boreholes and geophysical measurements reveal the deep canyon-like valley system of this river, which is largely filled with glacial sediments, as well as the fluvial (river) deposits in northern Poland, northern Germany and the southern North Sea. Especially in Poland and Samland these river sediments are rich in amber .
In the Eocene
The Eridanos drained areas of a subcontinent that included parts of what is now Scandinavia and Russia as far as the Urals . On this subcontinent, the so-called “ amber forest ”, which supplied the resin for the Baltic amber , grew over a period of around 20 million years . To the southwest of this area was a marginal sea of the Atlantic Ocean. The Eridanos was the union of two great source rivers. The main arm came from northwestern Russia. Onega and Ladoga lakes and the Gulf of Finland mark its former course. A second arm came from the north and flowed through what is now the Gulf of Bothnia . During the Priabonian (Upper Eocene) this river flowed into an extensive, at least 115 km wide delta (Chłapowo-Samland Delta) around the area where the Gdańsk Bay (Baltic Sea) is located today . From the sediments that the Eridanus deposited in its delta, the so-called blue earth was created , in which by far the largest part of the Baltic amber is found. However, it is also argued that the amber deposits in this area can primarily be explained by sea transgression and not, or only to a small extent, by river transport.
In the Pleistocene
In the Pleistocene, the Eridanos delta shifted further west. Caused by the global climate deterioration in the transition to the Pleistocene, the sea level sank worldwide and the southern parts of the Baltic Sea area became landlocked. With 2,700 km it reached its greatest length comparable to the Danube today. The late Eridanos Delta in the area of the North Sea had dimensions that can be compared with those of today's Amazon or the Mississippi . The Oder and Rhine were water-rich tributaries from the south. Late Tertiary quartz sands in the subsoil of Schleswig-Holstein and on Sylt ( Morsum cliff ) could be identified as delta deposits. Boulder finds in the Netherlands and investigations of sediments from the subsurface of the North Sea contributed to the reconstruction of the main tributaries of the Eridanus, and brought the finding that the river dried up at the latest in the course of the Cromer complex (Cromer warm period about 700,000 years ago) .
Relationship between Eridanus and the Baltic Glacial Current
The literature also takes the view that only the drainage system in the Eocene, in which the Baltic amber was transported to the area of today's Gdańsk Bay, can be correctly identified with the term "Eridanus" introduced by Barbara Kosmowska-Ceranowicz. Later drainage systems in the area of today's Baltic Sea in the period from the Miocene to the Pleistocene were created independently of this and can be correctly referred to as "Baltic glacial stream" or "Baltic main stream".
Individual evidence
- ↑ a b B. Kosmowska-Ceranowicz: Bernstein - The deposit and its formation. In: Amber - Tears of the Gods. P. 165, Bochum 1996. ISBN 3-921533-57-0 .
- ↑ Gerda Standke: Bitterfeld amber equals Baltic amber? - A geological space-time consideration and genetic conclusions. - In Exurs.f. and publ. DGG , 236: pp. 11–33, Hannover, 2008.
- ↑ Meyer & Bartholomäus: Baltic Urstrom and the Eridanos - a clarification. In: Geschiebekunde aktuell 29 (2): 57–58, Hamburg, Greifswald 2013.
literature
- M. Ganzelewski: Formation and deposits of Baltic amber. In amber - tears of the gods. Pp. 11-18, Bochum 1996, ISBN 3-921533-57-0 .
- B. Kosmowska-Ceranowicz: Amber - The deposit and its formation. In amber - tears of the gods. Pp. 161-168, Bochum 1996, ISBN 3-921533-57-0 .
- Küster H .: The Baltic Sea - a natural and cultural history. Pp. 24-25. CH Beck 2004
- JG Zandstra: Geologically onderzoek in de stuwwal van de Oostelijke Veluwe bij Hattem en Wapenveld. Mededelingen Rijks Geologische Dienst, NS 22: 215–260. Haarlem 1971.