tag:blogger.com,1999:blog-1237916293658671536.post6377333096745583190..comments2015-01-19T11:32:42.212-08:00Comments on My Southern Adventure: The good and bad..Anonymoushttp://www.blogger.com/profile/06778283197527634793noreply@blogger.comBlogger1125tag:blogger.com,1999:blog-1237916293658671536.post-18697216115972042592014-07-11T20:24:57.030-07:002014-07-11T20:24:57.030-07:00Hi Corey,
Though it's somewhat difficult to t...Hi Corey,<br /><br />Though it's somewhat difficult to tell from the photo and not hold it in my hand I'd say that's a pretty classic metamorphic rock (cooked deep underground) called a gneiss. The banding is formed by shearing deep underground over geological time (many many millions of years). Shearing is kind of like pushing a deck of cards from the bottom on one side and the top on the other so the cards slide over each other, this stretches the rock when it's in a kind of plastic state due to the pressure and heat down there, thus bands form. I'd take a stab and say that the rock is Archaean aged, somewhere around 2500 - 3000 million years old (2.5 - 3 billion). So pretty damn old.. Most of Antarctica (theoretically) is ancient cratonic rock, like in Western Australia (Yilgarn and Pilbara cratons) which you may have heard of, so this type of rock would be pretty common there, along with other metamorphic rocks. Antarctica was about 100 million years ago still completely attached to the southern margin of Australia and only completely separated about 30 million years ago, so the Geology has similarities to the western 2/3 of the country. Would like to head down to Antarctica, and not for lack of trying, getting a job down there is tough with my skill set. Stay well and great blog.<br /><br />cheers,<br /><br />J.Jeshttps://www.blogger.com/profile/13746611410510036091noreply@blogger.com