The Magdalenian epoch is divided into six phases generally agreed to have chronological significance (Magdalenian I through VI, I being the earliest and VI being the latest). The earliest phases are recognised by the varying proportion of blades and specific varieties of scrapers, the middle phases marked by the emergence of a microlithic component (particularly the distinctive denticulated microliths), and the later phases by the presence of uniserial (phase 5) and biserial 'harpoons' (phase 6) made of bone, antler and ivory.[3]