Klei-ijzersteen met boorgaten, - in de keileem van de groeve Osse te Losser

In the clay-pit of the brickfactory 'Osse' in Losser, a thick layer of boulderclay is present. This boulderclay is mixed with 60% glauconitic sandstone of Lower Eocene (Bartonian) age which has been brought upwards from low levels by the action of ice. In the sandstone pebbles of clay-ironstone occur, sometimes partly covered with remnants of oystershells and very often pierced by boring organisms. In the close vicinity of the clay-pit, deposits of Barremian age are present. These deposits contain heavy banks of clay-ironstone. It is supposed that during the Lower-Eocene period, a sea eroded the Barremian coast.