Kinetics of plasma protein deposition and replacement from a shear flow of full strength and diluted blood plasma onto prewetted glass were studied both numerically and experimentally. A band of fibrinogen moving down the adsorbing surface was predicted and observed The band was shown to define the region where blood platelets subsequently adhered to the surface. Since platelet adhesion is a fundamental component of thrombosis, this observation is potentially pertinent to the long-sought mechanism that determines where thrombus forms during shear flow of blood through artificial devices. The discrepancies between the mathematical model and experimental observations are explained by the presence of the natural convection, arising from density differences between plasma and the wetting fluids.