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Column: Limestone collapses make this quaint tourist town deadly
Rudi Kiefer

Popular for its natural beauty, the State of Minas Gerais, Brazil, has been haunted by tragedy recently. A deadly rock collapse smashing tourist boats on January 8 received little coverage on American news media. 

Some 21 million people live and work in this state focused on agriculture, mining and tourism. Many Brazilian towns are a unique blend of cultures. Downtown areas with vivid colors and simple boxy structures resemble ones you’d see in Puebla, Mexico. Away from downtown, stucco-clad apartment buildings with white walls, neat exterior and red baked-tile rooftops would fit into Munich or Frankfurt, Germany. In the western part of the state, the landscape bears  resemblance to portions of Georgia and North Carolina. A complex system of rivers and artificial lakes overlays the geology of limestone and older rocks. Comparable in size and popularity to Dahlonega, the town of Capitólio is a tourist favorite. 18 miles away, Furnas Dam turns the Rio Grande into a twisting lake, similar to Georgia’s Allatoona but deeply embedded in spectacular limestone canyons.

When limestone formed on ancient ocean bottoms, it settled in so-called “beds”, or layers a few feet thick. Vertical cracks leave the more solid parts standing as towers. Where flowing water has enlarged the cracks, caves have formed deep in the bedrock. Limestone is vulnerable to collapse. The angular shape of the beds and the deep breaks that separate them make it behave like a poorly stacked pile of cinderblocks. Strong rains had loosened the joints last week. On January 8, a large number of tourists on pleasure boats were cruising the lagoon, enjoying the views of steep canyon walls and towering limestone formations. 100 feet higher up, people standing at the canyon rim noticed that one of the towers was beginning to move. It was too late to rush the boats out of the way as the tower toppled over and crashed into the water, killing 7 vacationers.

There’s no “Told You So” effect because limestone can collapse without warning even weeks after heavy rainstorms. More preventable but even more tragic was the earth dam collapse in Brumadinho, 95 miles from Capitólio, which took 270 lives in January 2019. But last week’s disaster couldn’t be foreseen by technology. As a relative of the limestone that forms Lookout Mountain and Pigeon Mountain in our own state, the Capitólio Canyon bedrock combines natural beauty with serious hazards in some spots.

Rudi Kiefer, Ph.D., is a professor emeritus of physical science at Brenau University. His column appears weekends and at