Off the coast of Belize, there is an almost perfectly round hole in the sea that is nearly 1,000 feet across and more than 400 feet deep. Now, new research taken from this natural phenomenon is offering scientists clues as to what really happened to the ancient Mayan civilization. Hint: It has everything to do with water. Or rather, lack of.
Minerals taken from Belize’s famous underwater cave, known as the Blue Hole, as well as close by lagoons, suggests a century-long drought caused the demise of the Mayan civilization, Discovery reports. The findings showed that two extreme droughts occurred between A.D. 800 and A.D. 900 and A.D. 1000 and A.D. 1100 – just around the time the Mayan civilization collapsed.
From A.D. 300 to A.D. 700, the Mayan civilization prospered in the Yucatan peninsula. There, they built astounding pyramids, mastered astronomy, and developed both a hieroglyphic writing system and a calendar system; the same calendar which is famous for allegedly predicting that the world would end in 2012.
After A.D. 700, the Mesoamerican civilization’s building activities slowed and the culture fell apart as warfare and anarchy became more common. Historians have speculatively tied the culture’s decline with everything from the ancient society’s fear of malevolent spirits to the loss of favored foods, such as the Tikal deer. But it seems it was drought that eventually led to their ultimate defeat.
The evidence for a dry spell being the final straw for the ancient society has been growing in recent years, with scientists closely investigating the effects of drought for about two decades. A 2012 study in the journal Science “inspected a 2,000-year-old stalagmite from a cave in southern Belize and found that sharp decreases in rainfall coincided with periods of decline in the culture,” according to Discovery. However, the information came from only one cave, which meant it was difficult to make predictions for the region as a whole, André Droxler, study co-author and an Earth scientist at Rice University, said.
To closely investigate the Blue Hole, the research team drilled cores from the sediments in the lagoon, as well as in the Rhomboid reef nearby – thereby broadening the range of the study. Regarding the process behind drilling the cores, Discovery states:
“During storms or wetter periods, excess water runs off from rivers and streams, overtops the retaining walls, and is deposited in a thin layer at the top of the lagoon. From there, all the sediments from these streams settle to the bottom of the lagoon, piling on top of each other and leaving a chronological record of the historical climate.”
Droxler told Live Science, “It’s like a big bucket. It’s a sediment trap.”
Droxler and his colleagues analyzed the chemical composition of the cores, in particular the ratio of titanium to aluminum. As rain falls, volcanic rocks containing titanium sweep into streams that eventually reach the ocean. Thus, low ratios of titanium to aluminum correspond to periods of less rainfall, Droxler said.
The team discovered that during the period between A.D. 800 and A.D. 1000, when the Mayan society collapsed, there were just one or two tropical cyclones every two decades, as opposed to the usual five or six. After that, the Mayans traveled north, building at sites such as Chichen Itza, in present-day Mexico.
But the new findings also suggest that between A.D. 1000 and A.D. 1100, during the height of the Little Ice Age, another major drought struck. And this period aligns with the fall of Chichen Itza, fortifying the case that drought helped bring about the long decline of the Mayan civilization.
“When you have major droughts, you start to get famines and unrest,” Droxler said.
Scientists believe drought hit the area the Mayans inhabited so severely due to a shift in the intertropical convergence zone (ITCZ). The ITCZ is a weather system that usually pours water on tropical regions of the world and generally pelts the Yucatan peninsula with rain in the summer, while it moves farther south in the winter. Many have suggested that during the Mayan decline, this monsoon system may have missed the Yucatan peninsula altogether, leaving Mayans without the heavy rains that were typically expected.