lacks the expected positive gravity anomaly? Although sourced at shallow depths, sharp potential field anomalies can sometimes inform us about geology at depth. Figure 3 shows portion of the residual RTP image from a detailed airborne magnetics survey in Northern Australia. Rock types in the area comprise a series of sedimentary units, some of which are strongly pyritic; no magnetic pyrrhotite or magnetite is present in these units. The ground surface is rubble and alluvium covered. The residual RTP image is characterised by a pattern of sharply defined low order (5-15 nT) magnetics anomalies of obviously shallow origin, most of which are associated with drainage features. However, the highlighted magnetic lineament is not drainage-related. One interpretation might be that this response outlines a fault, where iron mobilised to the surface from pyritic sediments at depth has focussed the distribution of surficially developed maghaemite along the fault trace. There is support for this fault at depth from drill-hole results. So, with real world potential field responses, appearances may be deceiving and a bit of lateral thinking rather than a conventional interpretation can sometimes be called for. Figure 3.  RTP magnetics surficial anomalies. The ASEG in social media The ASEG has just joined Instagram https://www.instagram.com/aseg_news/ – so go on, give us a follow! We’d love to share your photos too, so please email Kate Robertson at communications@aseg.org.au if you have any images you would like featured. We know not everyone is on Instagram, but you can also find us on a variety of other social media platforms too! We share relevant geoscience articles, events, opportunities and lots more. Facebook: https://www.facebook.com/AustralianSocietyOfExplorationGeophysicists LinkedIn company page: https://www.linkedin.com/company/australian-society-of-exploration-geophysicists/ LinkedIn group: https://www.linkedin.com/groups/4337055/ Twitter: https://twitter.com/ASEG_news Youtube: https://www.youtube.com/channel/UC-dAJx8bXrX5BEudOQp4ThA  Minerals geophysics 39 PREVIEW JUNE 2019