New experiments on the interrelationship of clay minerals, solution properties, and postdepositional remanent magnetization (pDRM) provide interesting insights into pDRM acquisition. We have found that clay mineral content, composition, and solution conductivity affect pDRM strongly. With increasing clay concentration or electrolyte concentration, pDRM intensity decreases. Clay minerals may also be responsible for the inclination shallowing of pDRM. Different clay minerals behave differently: for example, montmorillonite diminishes pDRM intensity more rapidly than kaolin. Anson and Kodama (1987) have suggested an electrostatic model to explain their results of a similar study. However, we cannot explain all of our results by using their electrostatic model. To us, it seems that colloid coagulation is the key to explaining the results. Two kinds of forces exist in a colloidal solution: electric repulsion and van der Waals attraction. In low electrolyte concentration solutions, repulsion is larger than attraction. Strong Brownian motion is, therefore, required to enable the particles to cross over the repulsive energy barrier in order to stick to each other. But in high electrolyte concentration solutions, repulsion becomes relatively small, and particles stick together much more easily. Thus the effective mass of the grain becomes larger (clay+magnetite), but the magnetic moment remains the same, and hence the magnetic troque is relative less effective. As a result, the magnetic carriers do not align effectively in the direction of the ambient field, making the pDRM intensity weaker. ¿ American Geophysical Union 1990