The possible relevance of the Soret effect in geoscientific studies is discussed. In particular, the question is addressed of whether the observation that salinity generally increases with depth in geologic basins can be explained by this effect. We proceed from the fact that salinity increases with depth, in many cases almost precisely linearly at larger depths. This suggests that salinity may be interdependent with the geothermal gradient that behaves in precisely the same way. Our work on a transient analysis suggests that the timescales involved in establishing corresponding steady state salinity distributions in the presence of a temperature gradient could be on the order of 100 million years.