Polarisation in the horizontal plane of a 20 s Rayleigh wave propagating through an uniform, anisotropic region with oriented pyrolite. The amount of pyrolite decreases linearly from 40 per cent at 20 km depth to 0 at 100 km depth, its symmetry axis is dipping by 45° from the horizontal plane, and the azimuth relative to north is 20°. The azimuth (relative to north) of the propagation direction is 170°, corresponding to a backazimuth of 350°.