Landen Formation - Lithology

Lithology

The Landen Formation can be maximally 150 meters in thickness. It is subdivided into five only regionally recognized members:

• The Swalmen Member, lagoonal clay, sometimes with small lignite layers;
• The Reusel Member, green sandy clay, loam and sand;
• The Liessel Member, mica, pyrite and glauconite bearing clay, containing plant fossils;
• The Orp Member, greenish grey sand;
• The Gelinden Member, calcareous clay.

Some of the sandy layers can have been made into sandstone by diagenetic processes. The whole formation is interpreted as one megacycle: the lower parts (Swalmen and Orp) represent a marine transgression, while the upper parts (Reusel and Liessel) represent a regression.