b'Magnetics in the mountainsFeatureof magnetic values is just under 5000nT. The magnetic survey was flown with a terrain clearance of 80 m. unfortunately the line spacing and flying height are not as tight as the previous Indonesian examples.The stippled green area in the topographic image corresponds with Tertiary basalt, while most of the high points are Cambo-Ordovician sandstones. Points of interest are Mt Pearse, the arcuate ridge in the south west, and Valentines Peak and Companion Hill in the north. Mt Cripps is the V shaped edge to the plateau in the south east and the river cutting the plateau in the north is the Hellyer River. The infamous hairpin decent into the Hellyer Gorge is just off the image to the north east. Just to the south west of Mt Pearse the Hatfield and Coldstream rivers dig into the basalt sheet to create sharp breakaways. Each of those points of interest is associated with a corresponding pattern match in the magnetic data, and before drawing lines on an interpretation it would pay to understand what has a geological source and what is just topography.Figure 10 shows the forward modelled magnetic data, assuming a constant 0.01SI susceptibility and the upward continued, pseudomag filtered topography. At the time of the survey, the magnetic field in this area had a declination of 13 and inclination of -72. A field strength of 65000 nT was used for the forward model.As we might expect from the previous example, the two data Figure 6.Sun shaded image of topography that has a range of 1800 msets shape match very well. The forward modelled data shows (top), and comparison of the magnetic field computed from a homogeneousfewer edge effects than the Indonesian example, perhaps earth with topography using MAGFOR3D (middle), and upward continuedbecause the core of the mesh is a little further from the coast in pseudomag transformed topography (bottom). All images use a linear colour stretch. Graticule squares depicted are a 20 x 20 km grid. this example.Figure 7.Comparison of forward modelled topography using MAGFOR3D (red and left axis in nT) with re-scaled pseudomag topography upward continued (gold and left axis) and SRTM DEM (blue and right axis).JuNE 2020 PREVIEW 38'