Surface magnetic permeability measurements on some of the Taranaki ironsand deposits using anin situpermeability bridge are reported. The variation of iron ore concentration along the coast from Wanganui to Patea is discussed with particular reference to the effect of topographical features such as river mouths on the distribution. It is found that such features have a marked effect, indicating that sampling techniques may lead to erroneous values for the amount of iron ore present. It is concluded that the mechanism responsible for the concentration of the ironsands is probably a combination of sea- and wind-sorting, with the latter being the more efficient.