Weathering a Maya mystery.

• Author: Mackey, Chris
• Position: Collapse of an ancient civilization

For years scholars have speculated about what caused the collapse of the classic Maya civilization around A.D. 800. One of the world's great civilizations, the Maya date back to 2,000 B.C. and had a population of more than four million people. But for some reason, between A.D. 750 and 900, population decreased and construction of new temples and buildings ceased.

What brought on this decline is hard to determine. Archaeologists suggest that a combination of population pressure, disease, environmental degradation, and civil warfare devastated the Maya empire.

Recently, a group of researchers at the University of Florida at Gainesville published data that provides archaeologists with concrete information about climatic conditions at the time of the Classic Maya collapse. By analyzing sediment cores from two lakes in the northern lowlands of Mexico's Yucatan Peninsula - Lake Chichancanab and Punta Laguna - David A. Hodell, Jason H. Curtis, and Mark Brenner have reconstructed a climatic record for the past eight thousand years. They found that the driest period in the Holocene epoch occurred between A.D. 800 and 1,000, which coincides with the collapse of the Classic Maya civilization.

"This drought seems to have been somewhat protracted, maybe lasting a century or more with a peak that could have been on the order of several decades," says Fisheries and Aquatic Sciences professor Brenner.

The University of Florida team cored sixteen feet into Chichancanab's lake bed to analyze the stable isotope geochemistry of shells from snarls and ostracods preserved in the sediment. "The organisms formed their carbonate shells with an oxygen-18 to oxygen-16 ratio that was at or near equilibrium with...