Display ranges chosen for the density and neutron porosity logs such that the two curves will overlay at all porosity values providing the matrix is pure quartz and the pores are filled with fresh water. The most common overlay spans two tracks, with the density reading from 1. 9 to 2. 9 g/cm³, and the neutron in sandstone porosity units from 0. 45 to ?0. 15 vol/vol.