A crystal refraction experiment was conducted in August 1965 in Hudson Bay in which nine university and government crews participated. Good quality data were obtained from 41 shots providing sufficient data to permit time-term analyses of both Pnand P1arrivals. No consistent intermediate arrivals were identified leading to the consideration of a two-layer crustal model. Pntime-terms indicate that the depth of the Mohorovicic discontinuity is between 26 and 41 km.