The Mainz Basin (German: Mainzer Becken) or Rhine-Main Basin^[1] is the name given to a Cenozoic marine basin that covered the area of the present-day region of Rhenish Hesse in Germany about 38 to 12 million years ago (38 - 12 mya). The Mainz Basin was a bay or sea inlet, that for a short time in the Palaeogene period connected the then North Sea (part of the gradually widening North Atlantic during the Palaeogene) with the Paratethys Sea (part of the shrinking Tethys Ocean).

You can help expand this article with text translated from the corresponding article in German. (December 2012) Click [show] for important translation instructions. View a machine-translated version of the German article. Machine translation, like DeepL or Google Translate, is a useful starting point for translations, but translators must revise errors as necessary and confirm that the translation is accurate, rather than simply copy-pasting machine-translated text into the English Wikipedia. Consider adding a topic to this template: there are already 9,119 articles in the main category, and specifying|topic= will aid in categorization. Do not translate text that appears unreliable or low-quality. If possible, verify the text with references provided in the foreign-language article. You must provide copyright attribution in the edit summary accompanying your translation by providing an interlanguage link to the source of your translation. A model attribution edit summary is Content in this edit is translated from the existing German Wikipedia article at [[:de:Mainzer Becken]]; see its history for attribution. You may also add the template {{Translated|de|Mainzer Becken}} to the talk page. For more guidance, see Wikipedia:Translation.

• Mainz Sand Dunes
• Paris Basin