Coongra 1 stratigraphic well, located at Latitude 27º 8´ 15"S, Longitude 134º 8´ 20"E was drilled to 200.20 m total depth in Cretaceous sediments of the south-western Eromanga Basin, in an area of shallow basement. Two drill cuttings samples taken from the depth interval 188.3-191.2 m and from TD 200.2 m contain marine dinoflagellates that correlate with the Early Aptian Odontochitina operculata Subzone a. At 145.8 m depth, a non-marine claystone contained only spores and pollen of general Early Cretaceous affinities. A marine algal cyst and spore-pollen assemblage recovered from 106 m depth is probably Late Aptian, correlating with the O. operculata Subzone c. The dominantly sandy, marginal-marine sediments encountered from below 83.5 m to TD reflect their depositional position atop a basement high. They correlate lithologically with the Cadna-owie Formation, and chronologically with the marine mudstones of the Wallumbilla Formation, a unit that was deposited throughout most of the Eromanga Basin from the Early Aptian to Middle Albian. The sedimentary sequence found in the well can be related to the eustatic sea level changes that controlled the depositional environment elsewhere in the basin.