In 1944, while Mr. H. B. Owen, geologist of the Bureau of Mineral Resources, was travelling by road from Port Lincoln, South Australia, to Norseman, Western Australia, he collected specimens of the Tertiary rocks for micropalaeontological examination. A detailed report on these samples has never been put on record, but, as the area is now being investigated for the possibility of oil accumulation, the samples have been examined and this report prepared. Some interesting observations made by Mr. Owen during the trip are incorporated here. The most important results of the micropalaeontological examination of these limestones are: 1. The discovery of extensive deposits of upper Eocene age both in outcrop and in subsurface sections; 2. The similarity of the upper Eocene to lower Miocene stratigraphical sequence in the coastal area of the Nullarbor Plains with that found in portion[s] of the Carnarvon Basin, Western Australia, in the Adelaide Basin, South Australia, in north-western Victoria, and in the Torquay area, central southern Victoria.