Also, in the case of the halberds, the great rarity of any specimens of bronze blades which can be classified as halberds indicates that the form of implement practically ceased to be used when bronze came into use in Ireland. As the copper celts show a gradual transition from stone to metal forms, it seems reasonable to look for the prototypes of the copper halberd among the stone implements of the preceding period. In the Bann Valley many flint wedges or picks have been found, which may, perhaps, have influenced the copper halberds; and if a stone pick-like instrument was in use in Neolithic times, it may explain to some extent the prevalence of the metal halberd in Ireland in the copper period. When the blades were made larger, the curved form would come into existence, being suggested by the deer-horn picks already in use. Copper came into use in Ireland, we may suppose, in no sudden or violent manner. On the contrary, the transition from stone was probably of some duration. The use of copper made its way up through Europe, spreading from the lands of the eastern Mediterranean along the old trade routes of Neolithic times, influenced by the search for new deposits of ore. Though at first implements of copper, and even, perhaps, the metal, might be carried a considerable distance, an early use of the local ores seems to explain the case better. Whether this new knowledge of metal, coming from the eastern Mediterranean, first crept round by way of Spain, or struck across the Continent to the north and west of Europe, and so to Ireland, we cannot at present definitely say; the line of march, as indicated by the halberds, which are strangely deficient both in the south and the north of France, seems to point to north Germany and Scandinavia, by way of the rich ore-fields of middle Europe. But the archaeology of the Peninsula for this early period is at present too uncertain to speak with confidence. There are indications, even in Neolithic times, which, perhaps, point to Spain; but, again, there are relations which indicate a considerable correspondence with Brittany and the North of France in the early Bronze Age. The late Dr. Much ("Die Kupferzeit," p. 131) compared the Irish halberds with the Spanish and German examples, and came to the conclusion that the Irish halberds were later than the Spanish and earlier than the German. This view is supported by the form of the Irish halberds, which are more primitive in type than the German examples.