Bongo was impressed with the Bentheim Sandstone.  It looked like a Lower Cretaceous beach-type sandstone.  It had probably been deposited in the western margin of the Lower Saxony Basin about 130 million years ago.

Bongo recognised it as the same sandstone as the Schooneneek oilfield in The Netherlands.

There seemed to be some interfingering wedge-shaped lagoonal shales too.

(Bongo is in the center of the photo about 1/3rd of the way up from the bottom.)