Why some sinkholes are almost perfectly round

Ive been noticing a lot of questions from people asking why sinkholes can appear as almost perfect circles. Answers and theories include HAARP and other suspected sinister activities. In reality, there's actually a natural explanation

Sinkholes that collapse in such a fashion are known to geologists as "cover collapse" or "dropout" sinkholes. This type of sinkhole occurs in fine grained soil or sedimentary, kind of like the karst beddrock and volcanic ash in the area of the Guatemala sinkhole.

Heavy rains and underground water running in conduits through fine grained sediment, often causes voids in the material. Occasionally, these voids form into an arch shape. As time goes by, the tops of these arches are forced up and up by the water. When the arch reaches the surface, it collapses into a near perfect hole.

And thats how we get almost perfect circular sinkholes

The recent sink hole isn't actually a sink hole.

The top geologists were saying it is a volcanic piping feature. The area the city is built on is a huge thick layer of volcanic ash or pumice.

Essentially 35-45% of the city is on it, and will have to be relocated eventually.

They claimed that due to this, there will certainly be many more cave ins randomly in the future. The water run off from sewage, rain, etc, was causing the ash to collapse through or something.

But in this particular case, the reason it was circular is because it was a volcanic piping feature.

This is why there were very straight clean walls inside the feature. Because it is a ancient volcanic pipe. (Or something?)

This is not the original link I learned this from, but this is a link discussing it so it's worth a read.

geotripper.blogspot.com...

reply to post by muzzleflash


Thanks for that link. Either way I think I found the reason why sink holes are sometimes circular. The geologist even mentioned it on his website

Quite and interesting read too. It also appears as though sinkholes are only classified with sedimentary rock, rather than ineous, which includes the ash and pumice in the Guatemala cavern

i guess you could just think of the sink holes as a bubble in the ground that finaly surfaced.

the frequency they are occuring is still strange.

[edit on 8-6-2010 by pryingopen3rdeye]

Originally posted by pryingopen3rdeye
i guess you could just think of the sink holes as a bubble in the ground that finaly surfaced.

the frequency they are occuring is still strange.

[edit on 8-6-2010 by pryingopen3rdeye]

I dont think they are occuring more frequentl, I just think that with more media coverage, they seem to occur more frequently. It seems that a lot of them occur after heavy rain falls.

Alos, I shouldve clarified earlier, that the arch shape, when viewed from a 3D perspective resembles more of a dome shape

And I think this pretty much sums up my feelings on the sinkhole



Yeah random I know

Thanks for the explanation OW, i've been wondering about this and my kids have asked too.

I can pass on this little knowledge nugget now.

CX.