(a) Histograms of L_z (left) and ∣z∣ (right) when CND and ring particles last crossed R = 380 pc. The red dashed lines show the time-averaged half-mass height and L_z inside the ring region. (b) Scatter plot of the same data in the L_z–∣z∣ plane. Red and black points correspond to CND and ring particles, respectively; the dashed lines again show the ring averages. (c) Locations of events where the magnitude of the angular momentum changes by −10 kpc km s⁻¹ or more within 1 Myr. The left and right panels refer to the CND and ring samples, respectively.