Broadband shear wave signals from 15 deep South American earthquakes reveal small-scale variations of the D″ shear velocity discontinuity beneath the Cocos Plate. Deconvolution by average event source wavelets allows multiple event and California station combinations to be double-array stacked in 4 geographically separate reflection point bins with lateral dimensions of about 200 km. Reflections from the top of D″ are apparent in all 4 bins, with significant variations in timing and strength relative to ScS. The data are compatible with a discontinuous shear velocity increase 264 km above the core-mantle boundary that varies laterally in strength from 0.9% to 2.6%, with corresponding lateral velocity variations within D″.