Examination of eleven bores representing hundreds of Dublin, Port Gawler, Munno Para, and Yatala, permits a more comprehensive synthesis of the stratigraphy and micropalaeontology of the Adelaide Plains Cainozoic sequence than hitherto possible. Of the three members into which Aldingan and Janjukian stratotype Port Willunga Beds may be now informally subdivided, the upper two (including a prominent, mostly Janjukian, siliceous member) are readily recognisable in the Adelaide Plains. Due mainly to facies variation from the type section, Chinaman’s Gully Beds are mostly unrecognisable and lithological distinction between the Aldingan member of Port Willunga Beds and Upper Blanche Point Soft Marls cannot usually be made. However several microfaunal events in this interval can be traced throughout the area. The lower siliceous sequence in Blanche Point Banded Marls is distinct from the considerably younger siliceous member of Port Willunga Beds. Clay correlatives of Tortachilla Limestone, South Maslin Sands, and North Maslin Sands are referred to Muloowurtie Clays. Depth to bedrock varies from 376 feet in the north of the area (Section 97, A, Hundred of Dublin) to 1872 feet in the south (Grange bore, hundred of Yatala). Three of the eleven bores bottomed in the siliceous member of Port Willunga Beds, one in Blanche Point Banded Marls, one in South Maslin Sands, one in ?Permian glacigenes, three in Proterozoic or Cambrian bedrock, and two in more definitely Proterozoic bedrock.