Abstract: Apparatus for cutting erosive materials such as stone and the like includes a high-velocity, high-pressure water lance which can be raised and lowered as necessary. The lower end of the water lance carries a cutting head in the form of a nozzle assembly able to be rotated about the longitudinal axis of the water lance. The water lance is mounted upon a carriage which can be propelled in directions at right angles to each other and the water lance may be supported by a vertically-disposed truss, which itself may be relocatable about the longitudinal axis of the lance.