Ieper Group

The Ieper Group (Dutch: Ieper Groep; French: Groupe d'Ypres) is a group of rock strata in the subsurface of northwest Belgium. The group is subdivided into three marine formations, all formed during the Ypresian, a single age of the geologic timescale (55 to 49 million years ago, the oldest age of the Eocene epoch). Both age and group are named after the West-Flemish town of Ypres, for which the Dutch name is "Ieper".

The three formations of the Ieper Group are:

• The Kortrijk Formation, predominantly consisting of marine clay. It occurs in the west and north of Belgium.
• The Tielt Formation, consisting of fine sand and found in the subsurface of western and central Belgium.
• The Gentbrugge Formation, consisting of an alternation of clay, silt and fine sand. It crops out in East- and West-Flanders.

The Ieper Group lies stratigraphically on top of the Landen Group (upper Paleocene) and below the Zenne Group (like the Ieper Group early Eocene in age). Unlike the Zenne Group, the Ieper Group can also occur in more southern parts of Belgium, for example in the Mons Basin.