Greenland's icy mountains are not an obvious place to search for an archive of economic history, but a study just published in the Proceedings of the National Academy of Sciences shows that they provide one. Joseph McConnell of the Desert Research Institute, in Reno, Nevada, and (主题句）his colleagues have tracked economic activity in Europe and the Mediterranean地中海 over the centuries by measuring variations in the amount of lead in a core of Greenlandic ice.
Lead is a good proxy (代用） for economic activity because it is a by-product of silvermaking 银矿 (lead and silver often occur in the same ore, known as galena), and therefore of the money supply. Extracting silver from galena方铅矿 involves boiling off the lead. Winds from Europe carried to Greenland enough lead pollution from this process for it to be preserved in the layers of snow that, compacted 插入语, form the island’s ice cap. (解释这种测量方法的可行性）
Although the lead concentration in the core that Dr McConnell looked at shows many peaks and troughs, some overall patterns are clear. Emissions began to rise in around 1000BC. This corresponds to the spread of Phoenician traders and settlers from their home cities in the Levant into the western Mediterranean, and the consequent exploitation of galena mines in Iberia.伊比利亚
The rise and fall of Rome is also visible. An increase in lead concentration coincided with Rome’s victories in the Punic wars, against Carthage, the largest Phoenician腓尼基人 colony, during in the third and second centuries BC （公元前 before christ）. This was followed by a fall during the civil strife of the first century BC, a rise again when Augustus abolished the Republic and brought the pax Romana of the Empire, and another fall during the third century AD, when the state was engulfed once more by civil war, and also suffered invasion from the east.
The decline (衰弱)in lead pollution was enhanced by Rome’s switch from the silver denarius 便士, which had been increasingly debased with copper, to a gold standard. Even allowing for that, though, the European dark ages, during which Spain was occupied by the Visigoths, are clearly visible in the record—as is the point when civilisation starts to return with the rise of the Frankish state that, under Charlemagne 查理曼大帝, became the “Holy Roman Empire”, and with the takeover of Spain by the Umayyad caliphate.
1科学家通过测量格陵兰冰芯中铅含量的变化，研究在欧洲和地中海地区近几个世纪的经济活动。
2公元前1000年左右，铅排放量开始上升。与之对应，腓尼基商人及其殖民者 (开始) 从黎凡特乡城向西地中海扩张，随后他们在伊比利亚开采方铅矿 。
3罗马的兴衰也由此可见。铅浓度增加，恰逢罗马在‘布匿战争’中大胜迦太基，随后，浓度下降是由于公元前一世纪的内乱，而又再度崛起，因于‘奥古斯都’废除了共和国，而带来‘罗马和平时代’的太平盛世，但，公元三世纪，浓度再一次下降，当时国家再次惨遭内战以及东方的入侵。
4金本位制度让铅浓度降低 （后面扯了金本位制度的历史）