Ullernåsen and Husebyåsen, two hills of about 3 square kilometers covered with mixed forest, 5-10 km from the centre of Oslo, have been mapped geologically ( scale 1 : 1000 with contour interval 1 meter) by the author. Neighbouring areas, the Fornebu peninsula to the SW and the lowland of Bærum to the W, have been investigated before by Werenskiold ( 1) and Sæther ( 2).