Four faunal assemblages are present in the Lower Cretaceous shales and sandstones at Andamooka. Abundant Aptian foraminifera occur in the "toe dirt" immediately below the opal horizon. A notable discovery from recent sampling is that of late Pleistocene or early Recent estuarine sediments is several of the shafts, confirming the belief that during the late Pleistocene high sea levels extended the waters of Spencer Gulf northwards towards Lake Eyre.