Watch your step! An enormous sinkhole has opened up in the tiny municipality of Coromandel, in the State of Minas Gerais, Brazil. As Forbes reports, the 65-foot hole appeared overnight in the thick of a local soybean farm swallowing up earth, crops, and putting some 28,000 residents on alert. While some in the area had suspected a meteor was to blame for the cavernous hollow, geologists from the Federal University of Uberlândia have confirmed the sinkhole was in fact caused by the disintegration of the town’s underlying limestone bedrock.
In addition to farming soy, coffee, and corn, the region is active in mining pure calcareous limestone, a sedimentary rock that spans much of the area. The town of Coromandel, in fact, sits atop a large stretch of limestone.
While the sinkhole is the first to be recorded in the area’s modern history, geologist Trevor Nace is quick to point out that its occurrence is far from abnormal and should not be considered unexpected given the region’s limestone bedrock.
Nace says rain is slightly acidic. “As it percolates into the ground it can, over time, dissolve calcium carbonate into calcium, carbon dioxide, and water.” He adds, “As the limestone (calcium carbonate) dissolves it leaves voids underneath the ground and eventually the overlying weight of the sediment causes the area to collapse. This collapsed feature is a sinkhole.”
Nace also cites “Poço Verde/Green Well,” a local tourist destination that professors surmise was once a sinkhole that over time evolved into a lake.
Images via Coromandel’s press release and Google Earth