We present a simple phenomenological model of the c-axis resistivity i
n the layered cuprates, which accounts for the major features and syst
ematics of experiments on the c-axis resistivity, rho(c), for La2-xSrx
CuO4, YBa2Cu3O6+x and Bi2Sr2CaCu2O8. We associate the low temperature
semiconductor-like upturn in the c-axis resistivity with the suppressi
on of the planar density of states measured in the Knight shift experi
ments.