2.10.3. Borgloon Formation - Bo

Author: Laga (1988b).

Description: the continental and lagunary deposits start in Brabant by a layer of clay lenses with erosion and emersion characteristics, followed by an alternation of sand and clay layers. It is covered by grey white or brownish, cross bedded sand, locally lignitic. In Limburg the base is formed by a thick layer of grey and green clay, covered by black lignitic clay with horizontal layers of calcareous nodules and gypsum crystals, and an alternation of clayey and sandy layers. The top is formed by white yellowish, medium to coarse sand, with a lot of shells ( fragments) and alternating with 2 to 3 layers of grey white, compact clay with layers of black clay.

Stratotype: stratotypes have only been designated for the members.

Area: southern area of Brabant and Limburg.

Thickness: 20 m in Brabant and 10 m in Limburg.

Members: the formation is subdivided in NE Belgium into the Henis Mbr and the Alden Biesen Mbr. In the Brabant area, the formation is subdivided into the Heide bed, the Kerkom Mbr, the Boutersem Mbr and the Hoogbutsel bed.

Age: Early Oligocene.

Remarks: the formation is also discussed by Dumont (1849a, 1851), Glibert & De Heinzelin (1952, 1954a, 1954b), Janssen et al. (1976), Macar & Gulinck (1947), Maréchal (1993), Ortlieb & Dollfus (1873), Tavernier & Gulinck (1947) and Van Den Broeck (1881-1882, 1882, 1883b, 1893).