Models of mid-ocean ridge processes in which oceanic crust forms from a sill-like intrusion in the upper crust provide a link between geophysical studies of mid-ocean ridges and geological studies of ophiolites. These models predict that the lower crust forms by subsidence of largely solidified material beneath the sill. Such a downwelling provides a means to counter the normal tendency of entrained melt to separate from the higher density solid phase. In this case, the melt distribution may be controlled by the melt fraction that is just unable to escape the downward motion as much as by thermal constraints. Reasonable physical parameters for such a system yield melt distributions with a good match to the observed seismic velocity structure of the East Pacific Rise. Detailed estimates of lower crustal melt distribution may help to distinguish these two controls.