Diffusive mass transfer (diffusion creep) is diffusion at low to moderate temperatures and this occurs by pressure solution (requires the presence of a fluid medium ). Pressure solution occurs when pore fluids selectively dissolve material in zones under high pressure and reprecipitate material in zones of low pressure. Typically dissolution tends to occur on planes at a high angle to sima1 and precipitation tends to occur in the direction of sigma3. This is known as Riecke's principle. NOTE: if the strain sustained by the sample is irrotational, these directions correspond to e3 and l e1 directions respectively. This works on a combination of Poynting principle and Le Chatlier's principle. The table is after Durney who first showed the importance of pressure solution as a viable and important mechanism which can bring about large finite strain under certain conditions. In pressure solution, individual grains undergo dissolution on the face normal to the direction of maximum shortening (e3) and may undergo crystallization on the faces normal to the direction of maximum elongation (e1).This may produce such features as pressure solution seams or stylolites.