11.Apr.2011 Posted By: Brian Lipsey

How Are Sinkholes Created

The fundamental factor of all sinkhole development is the dissolving of the underlying limestone by slightly acidic water. As rain falls through the atmosphere, it absorbs carbon dioxide and forms a weak carbonic acid. As this water moves through the soil zone, it reacts with living and decaying plant matter becoming more acidic. The acidic water slowly erodes and dissolves limestone. This erosion eventually causes voids and fractures in the limestone into which overlying soils subside or collapses.  

 

 Droughts can also lower the groundwater levels, reducing the buoyant support prompting a collapse. The combination of droughts causing low water levels followed by excessive rainfall can accelerate sinkhole development.  Increased numbers of sinkholes can generally be attributed to changing or loading of the earth’s surface with development such as retention ponds, buildings, changes in drainage patterns, heavy traffic, drilling vibrations or a sudden or gradual decline in groundwater levels. In urban areas, all these impacts may occur at the same time, accelerating any sinkhole tendencies. Urban construction, coupled with limestone depths of less than 200 feet, contributes too many of the modern sinkholes.  

 

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