The name Eridanos, derived from the ancient Greek Eridanos, was given by

geologist A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, althoug ...

s to a river that flowed where the

Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain. The sea stretches from 53°N to 66°N latitude and ...

is now. Its river system was better known as the "Baltic River System". The Eridanos began about 40 million years ago in the

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

. By about 12 million years ago in the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

, the Eridanos had reached the

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea, epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the ...

area, where sediments carried by the river built an immense delta. The Eridanos disappeared in the early Middle

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

, about 1 million years ago, when the Ice Age

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...

s excavated the Baltic Sea bed. The Neogene uplift of the South Swedish Dome deflected Eridanos river from its original path across south-central Sweden into a course south of Sweden in the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Baventian Stage about two million years ago in the late early

, when it was about long, a little shorter than the modern

Danube The Danube ( ; ) is a river that was once a long-standing frontier of the Roman Empire and today connects 10 European countries, running through their territories or being a border. Originating in Germany, the Danube flows southeast for , p ...

. It began in Lapland, and then flowed through the area of the modern-day Gulf of Bothnia and

to western Europe, where it had an immense delta, which, it is reckoned, was comparable in size to that of the current-day Amazon River. Eridanos deposits in the Netherlands dating from the late Early Pleistocene Menapian glacial stage show the presence of

Scandinavia Scandinavia; Sámi languages: /. ( ) is a subregion in Northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. In English usage, ''Scandinavia'' most commonly refers to Denmark, Norway, and Swe ...

n erratic boulders ("Hattem Layers").Zandstra, J. G., 1971. ''Geologisch onderzoek in de stuwwal van de Oostelijke Veluwe bij Hattem en Wapenveld''. Mededelingen Rijks Geologische Dienst, NS 22: 215–260. These erratics are supposed to be transported by fluvial drift ice and are the first indicators in this part of the North Sea Basin of a major glaciation in the Scandinavian mountains. Most probably the reshaping of the Eridanos source areas in the Scandinavian mountains had already started during this glacial stage. During the succeeding Bavel Interglacial the fluvial system reached its largest size, but sedimentation rates already dropped at that time. The repeated buildup of the Scandinavian ice cap during successive ice ages after this interglacial resulted in a complete destruction of the source area, decapitating the fluvial system, and in the birth of a glacially excavated area surrounding the Scandinavian mountainous areas, in which region the Baltic Sea would later come into existence. During the first glacial stage of the Cromerian Complex, about 0.7 Ma ago, sedimentation in the Netherlands of the Baltic River System came to an end, indicating the end of the Eridanos. Remnants of the Eridanos are found all through northern Europe, from the current North Sea and the

Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...

at its western end to sediments in northern Lapland. Eridanos sediments in the Netherlands and the neighbouring North Sea can be recognized by a high content of transparent blue-grey, lightgrey, and colorless

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

in the sand, as well as in the gravel fractions. The color of the mainly coarse sands is grey-white, and in the Netherlands these deposits are, therefore, known as the White Sands ("Witte Zanden"). During the Early Pleistocene in the Netherlands fluvial deposits of eastern provenance mix with fluvial deposits of the river

Rhine ), Surselva, Graubünden, Switzerland , source1_coordinates= , source1_elevation = , source2 = Rein Posteriur/Hinterrhein , source2_location = Paradies Glacier, Graubünden, Switzerland , source2_coordinates= , so ...

. At that time the Rhine was far less important than the Eridanos. Sediment mixing can be recognized by the presence of a high proportion of "milky quartz" that is highly characteristic of sands and gravels deposited by the river Rhine. After the disappearance of the Eridanos, the river Rhine is left as the most important river in this part of the North Sea Basin.

References

{{reflist Former rivers Geology of the North Sea Pleistocene Neogene paleogeography Eocene paleogeography