Many of us are aware of sinkholes and their formation. The wiki says, they are fairly common and cause damage in parts of Florida, Kentucky, Missourie, Pennysylvania in USA. Apparently Michigan area has quite a number of them These have caught my imagination since the flooding in Guatemala city couple of days back. Apparently these are caused in places where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by circulating ground water. Also happens when water table falls dramatically etc..
These sinkholes can be huge and vary in size, from less than 1 to 300 metres (3.3 to 980 ft) both in diameter and depth!! Must be quite awesome sight to suddenly have sinkhole formed overnight, like its happenned in Guatemala city. But for Indians, we will be probably not so much in awe:-). We are so used to caving in happening in main arterial roads in cities (there is one near our house where the road always caves in even after they relay the road - its happenned so often, in the same place) and pathetic conditions in rural areas that natures' ways sometimes don't cause the wonder and amazement that it should:-).