Orientation of ocean floor basaltic rocks at time of cooling: A general method

During cooling of ocean floor basaltic lava, residual melt is segregated into vesicles which are still partially filled by volatiles. The segregated residual liquid and volatiles assume a preferential orientation in the earth's gravity field. The shape that the segregated material takes at the bottom of the vesicles is used as a criterion to determine the vertical orientation of the rock at time of cooling. This method is universally applicable to any rock which has passed through a molten phase prior to cooling.Contribution n^o 548 du Département Scientifique, Centre Océanologique de Bretagne