Based on the resistivity data below collected via Wenner array, determine the geologic structure of the subsurface: a) number of layers, b) depth(s) of interface(s), c) resistivities of the layers as accurately as possible.
Electrode spacing, a (m): 85, 128, 191, 287, 430, 645, 968, 1452, 2178, 3268
Apparent resistivity (Ω-m): 28, 34, 46, 66, 95, 133, 180, 232, 282, 320