Strata from the Permian and Triassic supergroups form a series of deep sedimentary basins and associated outliers in south-west Scotland. The strata are mostly water-bearing and form valuable local aquifers which are exploited for public and private supply. Secondary permeability provided by joint surfaces, bedding planes and other features is an important component of most of the aquifers. However the development is not universal; at some sites the intergranular permeability is dominant and at others both secondary permeability and intergranular permeability are lacking. Geophysical borehole logging is used to examine the secondary permeability.