From: P&G
Message: 12638
Date: 2002-03-09
----- Original Message -----From: Piotr GasiorowskiSent: Friday, March 08, 2002 10:37 PMSubject: [tied] The Morasko impactThe decline of the Funnel Beaker culture and the rise of the Globular Amphora culture towards the end of the 4th millennium have been explained by many authors as due at least in part to ecological changes, either natural (climatic deterioration) or anthropogenic (gradual deforestation). It has just occurred to me that there could be one more factor, so far neglected by everybody: the consequences of a meteoritic impact. Don't laugh, there was one at about the right time and place.Morasko is a gently sloping hill (just 154 m above sea level) on the northern outskirts of Poznan, west of the River Warta. I can actually see it from my window, and part of the Poznan University campus is located in its vicinity. The hill is the site of a well-preserved crater field, consisting originally of eight craters (one has been destroyed), very symmetrical and still quite deep (now most of them are filled with water); the diameter of the largest crater is ca. 110 m. What makes Morasko special is that is one of the not-too-many impact structures associated with actual meteorite fragments -- in this case, the debris of a huge IIICD iron meteorite. The total mass of the fragments found so far is about 288 kg (the first one, unearthed in 1914, was a lump of iron weighing 77.5 kg).The Morasko event is one of just a few identifiable meteoritic impact in postglacial Europe. It used to be dated to the early Holocene (ca. 10,000 BP), but recent research has demonstrated that the craters are much younger (mid-Holocene). The palynological and radiocarbon dating of the oldest organic deposits found at the bottom of the craters suggests 3000+ BP as the probable date of the impact.The effects of the impact are difficult to assess after 5000 years. Any small fragments of the meteorite rusted away ages ago, some larger chunks may still be buried very deep in the ground, and the entire mass (preatmospheric or on impact) is anyone's guess. While the craters on the wooded and mostly uncultivated hill (now a nature reserve) have luckily survived, there may have been other craters nearby that have been obliterated by farming -- or did the meteorite crash into the highest point of the Poznan area by sheer chance? A comparable event (also an iron meteorite that produced a similar number of similar-sized holes) at Kaalijärv (on the east coast of Saaremaa [Ösel], Estonia), now re-dated to ca. 800-400 BC, is known to have caused severe environmental damage on the island by starting forest fires even many kilometres from ground zero. The power of the blast may well have been within the 0.1-1 Mt TNT range.The Morasko meteorite landed right in the middle of a rather densely settled Funnel Beaker region. Immediate destruction caused by the heat radiation and the shock wave of the airblast was certainly limited to whatever had the misfortune to lie within a radius of a few kilometers. But large forest fires, perhaps even firestorms, may have raged for some time after the impact. The psychological trauma of the disaster and its long-range social, political and cultural consequences should be taken into account as well. It may have been one of the last nails in the coffin of the Funnel Beaker culture in the region of Wielkopolska (Poznan Province). Let me add that the focal area of the oldest known region of the Globular Amphora culture (from which the GA transformation began to expand shortly before 3000 BC) was located in Kujavia, just about 80 km ENE of Morasko.Piotr
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