About 1800 B.C., or the beginning of the Bronze Age in Britain, the subsiding land finally attained approximately its present level. At the same time the climate of western Europe deteriorated, becoming much more humid and rainy, and there set in a period of intense peat-formation in Ireland, Scotland and northern England, Scandinavia and North Germany, known as the Peat-Bog Period or Upper Turbarian. The peat-beds choked and killed the forests which had developed on the older peat-bogs, and grew up above the stools and fallen trunks, so that we have two layers of peat separated by an old forest. The forest level contains neolithic articles, the peat contains gold collars, bronze swords and pins, and other objects of the Bronze Age. This growth also went on even over high ground, which had not previously been covered by peat, for Professor Henry informs us that on Copped Mountain, near Enniskillen, and at other places in Ireland, Bronze Age cairns and tumuli are found resting on rock and covered by several feet of bog. Peat-beds on the Frisian dunes between two layers of blown sand are dated about 100 B.C., and some bogs in northern France were formed during the Roman period. There is also some much-disputed contemporary Latin evidence that at the time of the Roman occupation the climate of Britain was damp and boggy, while Gibbon (“Decline and Fall of the Roman Empire”), referring to the climate of central Europe at the beginning of the Christian era, points to some evidence that the climate was colder. This is, that the Rhine and the Danube were frequently frozen over, so that the natives crossed them with cavalry and wagons without difficulty, although at the present time this never happens. It is possible that this severe climate is referred to in the Germanic legend of the “Twilight of the Gods,” when frost and snow ruled the world for generations. The Norse sagas point to a similar cold period in Scandinavia. This lapse of climate occurred in the Early Iron Age, about 650 to 400 B.C., when there was a rapid deterioration from the high Scandinavian civilization of the Bronze Age. This deterioration of culture was probably the direct result of the increased severity of the climate.