Rocks in the Harz Mountains probably accumulated during an episode of Carboniferous subduction. Oceanic crust moving relatively southeast was consumed at a Benioff zone dipping southeast. Pelagic and abyssal sediments, graywacke, basalt, keratophyre, and other rocks were emplaced at the leading edge of the overriding plate. Present-day northwestward structural imbrication (vergence) reflects the original dip of the Benioff zone. As a block typical of the northern part of the Variscan belt of Europe, the origin of the Harz Mountains by subduction suggests that much of the northern margin of the belt may have originated in the same manner.