Megalithic tombs – new dating throws up a paradox

http://content.usatoday.com/communities/sciencefair/post/2010/08/barrow-tombs-of-prehistoric-europe-built-in-bursts/1 … it seems new dating evidence suggests the megalithic long barrows and passage tombs were built in a burst of activity over a few centuries around 4000BC. These predate the megalithic activity of around 3000BC, or that of around 2600BC and 2300-2000BC, and possibly around 1650BC. The new idea is published in the European Journal of Archaeology where Chris Scarre of Durham University looks at the dating of tombs from as far afield as Sweden in the north to Spain in the south. Great numbers were built at that time and then followed a long period of inactivity (or that is the suggestion). Hence, the idea of a ‘megalithic culture’ spreading across Europe gradually may have to be revised, though why they have so many similarities still has to be explained. Any spread of culture would have to have been extraordinary quick to influence regions as far afield as Iberia and Scandinavia within just a few centuries. However, there is always a clue – and if we look at Mike Baillie’s A Slice Through Time we find a major low growth tree ring event at 4350BC. This is about the dividing line between the Early and Middle Neolithic Periods in Europe and therefore it might be worth considering the possibility that whatever happened at 4350 gave rise to the building of tombs and barrows on a massive scale. This also explains why just a few bones were discovered in such tombs – they were in use for a short time. However, the construction of complexes such as Newgrange and Stonehenge came somewhat later in the sequence. Scarre claims the new evidence comes from improved C14 dating of materials such as birch bark, bone and stone left in the tombs, but I wonder if this means that the Carrowmore complex of megalithic tombs dates to around 4000BC?