A short programme of seismic exploration was undertaken in the southwest Arckaringa Basin in mid 1974. Shooting was confined mostly to an east-west line over the southwest end of the Tallaringa Trough. An interpretation of the geology of the trough based on seismic refraction velocities was carried out by comparing them with velocities from other parts of the Arckaringa Basin which have been identified with geological discontinuities. Sediments contained with the trough have thereby been interpreted as (?) Cambrian, Lower Permian and Mesozoic in age. Tentative maximum thicknessess assigned to these sediments at the centre of the trough are about 180m of Mesozoic and younger, 550m of Lower Permian (Stuart Range and Boorthanna Formations) and 700m of (?) Cambrian (Observatory Hill Beds). The total maximum depth to crystalline basement from both refection seismic data and calculated depth to magnetic basement is about 1450m below surface. The trough is fault bounded to the southeast by the Karari Fault, which can be plotted largely from geophysical information for about 100km in a northeasterly direction. The northwest limits of the trough are more difficult to ascertain from reconnaissance data, as it appears that the trough slopes gently southeast from the region of shallow crystalline basement of the central Arckaringa Basin. Stratigraphic drilling is recommended in the Tallaringa Trough to identify sediments present, and to provide control for interpretation of geophysical data. A limited programme of geophysical exploration to follow drilling is also suggested.