To the south of the previous area there is the Bükkic unit, which bears the signs of the transitional zone between the Western Carpathians and the Dinarides. Rock of the Bükkic occurs in the north Hungarian mountain Bükk. It consists generally of the Paleozoic shales, carbonates, and sandstones, but also overlying younger Mesozoic carbonates and volcanic rocks. Sedimentation continued to the Jurassic when the nappes of unclear vergence were thrust. The zone was later in the Cretaceous affected by low grade metamorphism. During the subduction of the Meliata-Halstatt Ocean in the Upper Jurassic, the back-arc basin evolved. This basin was later inverted and it was probably the root zone of the Mónosbél-Szarvaskő nappe.