Top: median metallicity in the velocity plane of the local neighbourhood of the RAVE sample. Left panel: 25 logarithmically spaced contours in the range spanned by the metallicity, i.e. [−0.70, 0.06]. Middle panel: same as the left one but shows contours (white) of the wavelet transform that mark the main over-densities in the velocity plane, and contours (green) that indicate significant metallicity differences (95% confidence) from its symmetric v_R region. Right panel: differences in the median metallicity for positive and negative v_R. The green contours are the same as for the middle panel. The numbered labels are points identified as depicting clear differences in metallicity, and whose characteristics are given in Table 1. Bottom: same for the GCS sample, with the labelled points given in Table 2. Left panel: now 25 logarithmically spaced contours in the range of [−0.34, 0.1].