GIANT SINKHOLES in the EARTH?!

Did you see the Fantastic Four movie with the Silver Surfer? If so, do you remember the giant sinkholes which formed in the Earth? (see trailer...)



....Well, it turns out that sinkholes are a REAL geological phenomenon!
Today, newspapers reported of a giant sinkhole that formed in the Earth in the tiny village of Schmalkalden, Germany.

The story of the sinkholes hit close to home as my family is from a village (see black arrow on map below) about 50 miles away from Schmalkalden (see red arrow below). What continent in Germany on?
If you answered Europe, you are correct. Sinkholes have also appeared in other areas of the world, such as the one which opened up earlier this year in the South American country of Guatemala (see picture below of a sinkhole that opened up in Guatemala City).

So what are sinkholes?
Sinkholes are all about water.
- Water dissolves minerals rocks in the earth, leaving residue and open spaces within the rock. (This is called "weathering".)
- Water washes away soil and residue from voids in rocks in the earth.
- Lowering levels of groundwater causes a loss of support for soft material in rock spaces which leads to collapse.
- Changing groundwater gradients (due to removing or introducing water to the system) can cause loose material to flush out quicker from the voids and the surface to collapse in response.
- Sinkholes can result from seasonal changes in the groundwater table, freeze and thaw of the ground, and extremes in precipitation (drought vs heavy rain).

For more on the sinkhole in Guatemala, check out National Geographic's website: http://news.nationalgeographic.com/news/2010/06/100603-science-guatemala-sinkhole-2010-humans-caused/