New York: The ancient Mayan civilisation may have collapsed due to a century-long drought, a new research suggests.
Researchers analysed minerals taken from Belize's famous underwater cave, known as the Blue Hole, as well as lagoons nearby, and found that an extreme drought occurred between AD 800 and AD 900, right when the Mayan civilisation disintegrated.
Although the findings are not the first to link a drought to the Mayan culture's demise, the new results strengthen the case that dry periods were indeed the culprit.
From AD 300 to AD 700, the Mayan civilisation flourished in the Yucatan peninsula. In the centuries after AD 700, the civilisation's building activities slowed and the culture descended into warfare and anarchy, 'Live Science' reported.
A 2012 study in the journal Science analysed 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.
The researchers in the new study drilled cores from the sediments in the Blue Hole of Lighthouse lagoon, as well as one in the Rhomboid reef.
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 and his colleagues analysed the chemical composition of the cores, in particular the ratio of titanium to aluminum. When the rains fall, it eats away at the volcanic rocks of the region, which contain titanium.
The free titanium then sweeps into streams that reach the ocean. So relatively low ratios of titanium to aluminum correspond to periods with less rainfall.
The team found that during the period between AD 800 and AD 1000, when the Mayan civilisation collapsed, there were just one or two tropical cyclones every two decades, as opposed to the usual five or six.
After that, the Maya moved north, building at sites such as Chichen Itza, in what is now Mexico.
The new results also found that between AD 1000 and AD 1100, during the height of the Little Ice Age, another major drought struck. This period coincides with the fall of Chichen Itza.
The findings strengthen the case that drought helped usher in the long decline of the Mayan culture, researchers said.