Abstract: It is shown by the results of free vibration column tests on clay taken from different depth below the o-cean bed that the shear medulus of clay is not a constant.It changes not only with shear strain level but alro withdegree of consolidation and.preconrolidated praseure,The relations between shear modulus and degree of consolida-tion and between shear modulus and preconsolidation prassure are estiblihed.