|Lapita pot from Tonga (source)|
Category Archives: sea
The Atlantic meridional overturning circulation affects the latitudinal distribution of heat, and is a key component of the climate system. Proxy reconstructions, based on sedimentary 231Pa/230Th ratios and the difference between surface- and deep-water radiocarbon ages, indicate that during the last glacial period, the overturning circulation was reduced during millennial-scale periods of cooling. However, much debate exists over the robustness of these proxies. Here we combine proxy reconstructions of sea surface and air temperatures and a global climate model to quantitatively estimate changes in the strength of the Atlantic meridional overturning circulation during the last glacial period. We find that, relative to the Last Glacial Maximum, the overturning circulation was reduced by approximately 14 Sv during the cold Heinrich event 1. During the Younger Dryas cold event, the overturning circulation was reduced by approximately 12 Sv, relative to the preceding warm interval. These changes are consistent with qualitative estimates of the overturning circulation from sedimentary 231Pa/230Th ratios. In addition, we find that the strength of the overturning circulation during the Last Glacial Maximum and the Holocene epoch are indistinguishable within the uncertainty of the reconstruction.
|Summary of thermohaline circulation (public domain, NASA)|
A total of 167 plates of two whale barnacle species (Tubicinella majorLamarck, 1802 and Cetopirus complanatus (Mörch, 1853)) have been found in the Upper Magdalenian layers of Nerja Cave, Mina Chamber (Maro, Málaga, southern Spain). This is the first occurrence of these species in a prehistoric site. Both species are specific to the southern right whale Eubalena australis, today endemic in the Southern Hemisphere. Because of Antarctic sea-ice expansion during the Last Glacial Period, these whales could have migrated to the Northern Hemisphere, and reached southern Spain. Whale barnacles indicate that maritime-oriented forager human groups found stranded whales on the coast and, because of the size and weight of the large bones, transported only certain pieces (skin, blubber and meat) to the caves where they were consumed.
According to the authors, this is the first case of consumption of whale meat and blubber ever documented in Europe.
PS- And what was the blubber used for (besides eating)? Our friend David Sánchez coincidentally just published two successive and quite interesting articles (in Spanish) at his blog on the lamps of the Upper Paleolithic: 1st part, 2nd part.
|A particularly beautiful lamp from Lascaux (Dordogne)|
Update (Jan 29): another finding of whale consumption in Magdalenian contexts unknown to me until now (h/t David) is from Las Caldas (Asturias). One of the two co-researchers is the same as the lead author of the Nerja paper → direct PDF link.
Update (Feb 22): David again added more interesting information on the matter of possible whaling in the Magdalenian period by pointing us to Colchón Rodríguez & Álvarez Fernández 2008, where they discuss (in Spanish) the presence of sea mammal remains in the cave of Las Caldas (Asturias): a seal tooth (pierced as to be part of a necklace or similar decoration), a pilot whale tooth (only initially worked), a sperm whale tooth (fully sculpted into low reliefs of whale and bison) and also several whale and other sea mammal bones used for tool-making (they made spear points on whale bone, as was documented years ago for Isturitz in the same period) and some mollusks, notably the shell of a whale barnacle (Coronula diadema).
Las Caldas (locator map) is some 20 Km. inland nowadays, in the Magdalenian period maybe 30 Km. or so. The whale barnacle suggests that whale meat was moved all that distance from the coast.
|In red the tsunami sediments
Measures: height of the wave at each location
A huge tsunami probably hit the northern parts of Doggerland (the emerged landmass of what is now the North Sea) some 8000 years ago. The evidence from this catastrophic event, which probably affected the earliest inhabitants of NW Europe in a catastrophic way comes from an underwater formation off the Norwegian coast known as Storegga, which was partly demolished by the force of the giant wave, as well as from sedimentary layers at various coastal locations. The wave reached more than 20 meters at the Shetlands, where it left a 30cm-thick revealing layer.