Bumbarlow 1 (TD 720.33 m) aimed to test the lithology and petroleum potential of the Cambrian section in the central part of the eastern Arrowie Basin. It continuously cored a sequence over 300 m thick of flat-lying Proterozoic sediments interbedded with lavas, which lies below 209 m of Mesozoic and 192 m of Tertiary and Recent sediments. The sub-Mesozoic section in Bumbarlow 1 contrasts markedly with the equivalently placed Cambrian sections penetrated in the Lake Frome 1-3 wells to the south-west and in Yalkalpo 2 to the south-east, where gently folded strata can be closely correlated with the Cambrian rock sequence in the Flinders Ranges. Rb-Sr dating of shale from within the Bumbarlow 1 Proterozoic section at 645 m depth suggests an age of 1360 +/- 140 Ma for the overall shale/lava sequence, thereby confirming that the Benagerie Ridge extends further north into the basin than was previously supposed. This drilling result has reduced the area of presumed Cambrian and Ordovician sediments lying to the east of the Flinders Ranges, within the eastern part of the Arrowie Basin, but has not reduced the petroleum potential of any such sediments if they exist in areas to the north and north-east of Lake Frome, where they may likely connect through to similar-aged deposits of the Warburton Basin. Drill dates: 4/4/1978-15/6/1978. GL 31.15 m, KB 32.0 m, SP 151, line 71-CFK. Status: dry - plugged and abandoned.