Mixed sand and gravel coastlines have a lot of research potential for both coastal resource management and scientific reasons. In recognition of this, a series of 3-dimensional physical model tests has been undertaken in order to examine the behavior of gravel and mixed beaches more closely. The 3-D physical model tests were carried out in the 3-D wave basic located at Franzius-Institute (Marienwerder) of University of Hannover, at a nominal scale of 1:1. During the study, measurements of beach profiles and of cross-shore and long-shore current data were taken, generated by oblique wave attack, along gravel and mixed beaches with a uniform slope and a trench. New formulae for predicting wave breaking depth index, breaking depth and height, undertow velocity, long-shore current velocity and step and berm elevation have been proposed. A new parametric profile model has been developed in order to predict the beach profile changes of gravel and mixed beaches with a uniform slope and a trench due to sediment transport.