出典:Wikipedia
出典:『Wikipedia』 (2009/06/18 23:10 UTC 版)
The Aalter Formation (Dutch: Formatie van Aalter, abbreviation: Aa; named after the town of Aalter in East-Flanders) is a geologic formation in the subsurface of northwest Belgium. The formation consists of marine clay and sand, deposited in the shallow sea thet covered northern and central Belgium in the Eocene epoch.