The potential permeability enhancement of a substrate that has been burrowed by a suite of fauna that inhabit geological firmgrounds (i.e. the Glossifungites ichnofacies) is investigated by using computer simulations, laboratory and field measurements to assess the effective permeability of a Pleistocene Glossifungites surface. All the testing methods indicate that the effective permeability of a substrate is markedly enhanced by the presence of sand-filled Glossifungites burrows in the low-permeability substrate. Furthermore, the permeability of these burrowed horizons can be well approximated by using a modified arithmetic mean that accounts for the degree of interconnectivity between burrows. These formulae are robust and, conceptually at least, can be applied to a variety of geological media and burrow configurations.