I just saw the sinkhole in Guatamala, and I was wondering. How exactly do they work? Is it just a straight drop in the deep ones when they open up, or. and what exactly in at the bottom of a sinkhole? I know they go from 1-300 meters deep, but what is at the bottom? And what happens when someone falls down one?
The Guatemala City sinkhole is 100 feet deep and almost 70 feet in diameter. It is a straight drop to the bottom. Its bottom, I would suspect, consists of dirt and debris that once comprised the roof of a remarkably large underground void, which collapsed into this void to create this large hole. This dirt and debris lies on the floor of the void that collapsed. However, it is not a real sinkhole. Instead, it is what geologists would call a piping feature. Real sinkholes are created by the dissolution of limestone, dolomite, nor marble. However, the “sinkhole”, which opened up in Guatemala City did not result from the dissolution either of limestone, dolomite, marble, or any other carbonate rock. Neither limestone, dolomite, nor marble underlie Guatemala City. Instead, uncemented, unconsolidated volcanic deposits composed largely of pumice and volcanic ash underlies all of Guatemala City. Thus, the dissolution either of limestone, dolomite, or marble did not and could not have created this large “sinkhole”. Instead, the Guatemala City “sinkhole” and a similar one which opened up in 2007, were created by the collapse of a large cavity that developed in very weak, crumbly Quaternary volcanic deposits. These deposits only have enough cohesion to allow them stand in vertical faces and develop large subterranean voids within them. The void, which collapse to form this “sinkhole” was formed by the a process called “soil piping” by which water flowing through the Quaternary volcanic deposits underlying Guatemala City washed fines out of them and progressively eroding coarser material to the point that a large underground void was created. Technically speaking, this hole is not a true sinkhole as it lacks any association with karst developed by the dissolution of limestone, dolomite, or marble. This hole is a spectacular of pseudokarst (false karst).
A sinkhole is basically a cavity that has formed underground, where the ground above it has given way, and collapsed. Depending on what has caused the sinkhole, there could be water in the bottom of it, or else, just what has collapsed into it (i.e. rocks) If someone were to fall down one, they would surely be killed, with little chance of rescue.
