The Tongeren Group is a lithostratigraphic unit (a sequence of rock strata) in the subsurface of Belgium. It consists of shallow marine, epicontinental and/or continental clays and sands from the Late Eocene to Early Oligocene epochs (between 37 and 30 million years old). The Belgian Tongeren Group correlates with the Dutch Tongeren Formation. The name was introduced by André Hubert Dumont in 1849.