Re: Wait...
King of the Americas said:
... so some kind of chemical reaction occurs 'possibly' during a volcanic erruption (I haven't seen these things at all volcanic hot spots), and when it 'splits' or erodes, these are the shapes it makes...?
Where might one see these things? I'd LOVE to see this first hand.
The particular location in the photos is the Devil's Postpile National Monument in East Sierra, California. The way it formed (and the way many other types of igneous rock form) has not only to do with chemical composition; a large part of it involves the way in which the lava deposit cooled. For example, foamy lava that has erupted and been thrown into the air will cool quickly, and be full of air pockets, thus you get pumice. Lava that stays hot long enough for the air bubbles to seep out, then cools quickly, forms hard and glassy obsidian. In the case of the Devil's Postpile, it was a pool of lava 400 feet deep. It cooled slowly and uniformly, and most important, solidly. As it contracted, it fractured into the hexagonal shapes. Another thing about the Devil's Postpile is that after it had cooled, it was run over by a glacier - that's why in the photos, the surface of the Postpile is not level, but grooved and rounded. Also, the glacier ripped off one side of the formation, so now there's a cliff where the columns are exposed. You can see little bits of columns laying on the ground at the cliff base where the glacier deposited them (and where some have presumably fallen off over the years).
Another very famous location that features the hexagonal basalt is Easter Island. A few book authors (like Von Daniken) didn't understand that hexagonal basalt is natural, so they used it as evidence that an "advanced civilization" lived there, which cut the rock.
Sometimes the columns don't fracture perfectly straight all the way down, like in this dramatic scene from Iceland:
Other places with basalt columns are Sardinia Italy, Devil's Tower National Monument in Wyoming (the one from the movie Close Encounters of the Third Kind), various places in Oregon, Scotland, and all over Micronesia.
King of the Americas said:
... *Did you check out the underwater city in Japan, via my link above?
Yeah....kind of creepy looking.
