The seismic refraction shooting experiments undertaken in the eastern Atlantic and on the neighbouring continental shelf are briefly described, and the results compared with previous work. The deep-sea results show that basaltic rocks lie immediately below the sedimentary layer, which is variable in thickness, with a mean of about 1 km. The basaltic rocks extend to the Mohorovičic discontinuity at a depth of between 9 and 13 km below sea-level. The results from the stations on the continental shelf at the mouth of the English Channel confirm that the basement rocks slope gently seaward; the value of this slope and the nature of the sedimentary cover vary with position.