Comparison of calculated a) k from Equations (1, 4), b) F from Equations (2, 5) and c) k from Equations (3, 6) to the observed values of permeability and formation factor in the unconsolidated glass beads and sands. The meaning of the different symbols is explained in the inset, where k(z) refers to Bernabé et al. Equation (4), F(z) to Equation (5) and k(F) to Equation (6). The vertical error bars (dark purple) represent the tolerances estimated for the Bernabé et al. model, δk/k ≈ ±30% and δF/F ≈ ±10%.