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Paleo Slide Set: Low Latitude Ice Cores: High Resolution Records of Climatic Change and Variability in the Tropics and Subtropics
Melting core samples
Core samples from Quelccaya were melted in closed containers by passive solar heating, bottled, and sealed with wax. The bottles were then shipped back to the United States for laboratory analysis. Two of the analyses performed on the cores are presented here, accumulation and the oxygen isotope ratio (known as d18O). Accumulation is a measure of annual layer thickness normalized to account for the compression of ice layers at depth and corrected for ice flow dynamics. The oxygen isotope ratio (a measure of the ratio of heavy oxygen (18O) to light oxygen (16O)) is a proxy measure for paleotemperature, though it also reflects changes in snow surface processes and water-vapor history.

One of the most salient features in the last millennium of climate history is the Little Ice Age, a loosely-defined period of cold temperatures and increased climatic variability that has been documented in many parts of the globe.* As this figure shows, the Little Ice Age is identified in the Quelccaya climate record as a period of 'colder' (more negative) d18O roughly bracketed between 1550 A.D. and 1900 A.D. The accumulation record is more complex, showing a pronounced wet period before 1700 followed by significantly drier conditions thereafter.

500-600 Early Intermediate: Regional centers of culture flourished in coastal valleys.

600-1000 Middle Horizon: Rise and establishment of 1, 2, or more highland empires (this period is divided into two eras, prior to 800 when Huari served as the center for a large highland empire, and after 800 when highland cultures continued to flourish despite the fall of Huari).

1000-1476 Late Intermediate: A number of regional culture centers rose on the coast.

1476-1532 Late Horizon: The highland Inca Empire quickly establishes hegemony over a vast region from Quito (now in Ecuador) to northern Chile.

Photo Credits:
Lonnie Thompson
Byrd Polar Research Center, The Ohio State University

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Last Modified: 12 October 2001

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