Abstract: In accordance with the invention, the stemming of blast holes, i.e. the covering (with peviously removed earth materials) of explosive charges placed in receiving boreholes drilled downwardly from generally horizontal surfaces in open-pit mines, involves the proper manipulation of a special vehicle relative to earth material cuttings that collect concentrically about the mouth of such a borehole during the drilling operaton. The vehicle carries a combination of earth-moving blades that can be raised and lowered as a unit and that comprises a transverse pusher blade mounted on one end of the vehicle and a pair of elongate auxiliary blades pivotaly mounted on and in mutually spaced relationship transversely of the pusher blade as arms which can be swung toward and away from each other. The auxiliary blades have respective tip portions turned toward each other, and are preferably arranged to stop short of meeting when swung together so as to accommodate the blast cord between such tip portions.