Innamincka no. 1 well was drilled to a depth of 12,638 feet KB and penetrated a sedimentary sequence of Mesozoic and Palaeozoic rocks ranging in age from Cretaceous to ?Devonian. Marine Cretaceous (Albian) carbonaceous mudstones and siltstones were entered at 1700 feet and at 3920 feet the well passed out of the marine Albian-Aptian sequence into non-marine arkosic sandstones of Neocomian age. Between 4620 feet and 5920 feet a non-marine sequence of grey micaceous sandstones and siltstones with coal bands of Jurassic age was intersected, followed by ?Triassic non-marine red, green and grey sericitic and dolomitic siltstone and white sandstone between 5920 and 6750 feet. At the latter depth the well passed into Upper Permian carbonaceous siltstones and sandstone with coal. An angular unconformity occurred between 7010 and 7040 feet where the well entered a sequence of redbeds dipping at 25 degrees. The sediments consist of red and green sandy calcareous siltstones and cross-bedded sandstones, the age of which is not known with certainty but is believed to be Devonian. Boring ceased in these rocks at 12,638 feet.