The shear wave velocity in near-surface basalt was inferred from low frequency reflectivity versus grazing angle measurements from the basalt-water interface at the East Pacific Rise. This data, together with previously reported low frequency measurements by Spudich and by Helmberger and Morris, are correlated with Christensen's high frequency determinations of shear wave velocity vs geologic age in small solid-basalt samples, through an analytical model of the velocity of sound in a randomly disordered two phase medium, in which neither phase acts as the host or matrix material (Budiansky, 1965). This theory, which appears to be qualitatively consistent with Hyndman's heuristic description of the ratio of solid rock to sediments/water in near-surface basalt, offers a plausible quantitative account of the observed relationship between the high and low frequency measurements, and a working hypothesis for the development of a geoacoustic model of the upper crust.