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Climatic Drying in Mesoamerica Between 2000 and 1000 BC and its Potential Role of Initial Settlement of Early Maya Civilisations in Peten, Guatemala

Abstract:

Unlike the collapse of the Classic Maya culture, which may have been related to a series of abrupt droughts on the Yucatan Peninsula in the 9$^t^h$ and 10$^t^h$ centuries AD, less is known about climate change at the time of initial settlement of early Maya civilisations in Pet$\acute{e}$n that occurred during the early preclassic period (~2000 - 1000 BC). We focus on the time period between 2000 and 1000 BC and present sedimentological, geochemical and pollen data from a sediment core taken in Lake Pet$\acute{e}$n Itz$\grave{a}$ ($16\deg$ 55$`$ N, $89\deg$ 50$`$ W), northern Guatemala, the deepest lake in the lowland Neotropics of Central America. The lake lacks surface outflows so that its water level is very sensitive to changes in the balance between evaporation and precipitation. Our results suggest a lake level lowering, i.e. drier conditions, during pre-Maya times between 2000 and 1000 BC. The lower lake level is marked lithologically by a shift from previously accumulated, laminated, deep-water clay to overlying shallow-water, gastropod-rich sediments, and by an increased amount of autochthonous calcite crystals. Additionally, our new pollen record from Lake Pet$\acute{e}$n Itz$\grave{a}$ documents a decline of tropical high forest taxa and an increase in pine and secondary taxa between 2000 and 1000 BC. This is interpreted to reflect increased openness of the vegetation, and together with evidence for lake level lowering, points to drier conditions in the region. The oxygen isotopic record from Lake Pet$\acute{e}$n Itz$\grave{a}$, however, does not show a significant increase in $\delta$$^1^8$O values between 2000 and 1000 BC as might be expected as a consequence of an increased evaporation and/or reduced precipitation. So a potential lake level lowering could not be confirmed yet by stable isotope analysis. Evidence for the onset of regional drying around 2000 BC is supported by a coinciding drying trend measured in a marine core off northern Venezuela (Cariaco, ODP Hole 1002C). Furthermore, paleoclimate archives from several lakes in Africa (e.g. low lake level in Lake Bosumtwi ($6\deg$ 30$`$ N, $1\deg$ 25$`$W) indicate a simultaneous drying phase in the northern tropical regions on both sides of the Atlantic Ocean. In contrast to the northern hemisphere, wetter climate conditions occurred after ~2000 BC in the southern hemisphere (e.g. rising water level in Lake Titicaca ($16\deg$ 0$`$ S, $69\deg$ 0$`$ W). We suggest that these climate patterns occurred as a consequence of a southerly displacement of the mean position of the Atlantic Intertropical Convergence Zone (ITCZ), which controls moisture distribution in tropical latitudes. Climate drying and consequent thinning of the dense tropical forest cover from 2000 - 1000 BC in the Guatemalan lowlands may have promoted the use of slash-and-burn farming practices and initial permanent settlement of early Maya.

Authors:

Mueller, Andreas and Anselmetti, Flavio and Hodell, David and Brenner, Mark and Ariztegui, Daniel and Islebe, Gerald and Grzesik, Dustin and McKenzie, Judith and Plötze, Michael and Hillesheim, M

Index Terms:

ClayGroup; clay; maya culture; Guatemala; climate change; Anselmetti, Flavio; Ariztegui, Daniel; Brenner, M; Grzesik, Dustin; Hillesheim, M; Hodell, D; Islebe, Gerald; McKenzie, Judith; Mueller, Andreas; Plotze, Michael

Further Information:

Date published: 2006