Tuesday, 31 May 2011

Geography Picture Of The Day - Terraces of Pammukale

I thought I would try some new, different things on this blog to try and make it a bit more visual as I realise that, normally, I just write a lot and so it doesn't look that exciting. Firstly I thought I would, as often as possible, write about a geography related picture that has interested me or made me stop and think.........

These are the snow-white terraces of Pamukkale in south west Turkey and I have never seen anything like these before and, because they look quite unusual, they caught my eye in a book I was looking at the other day. Pamukkale itself means 'Cotton Castle' which isn't hard to see why when you look at some of the images of these terraces.

 So, how do they form? Well, Pamukkale is located along a tectonic fault line and the area is full of hot springs. These hot springs are crucial in the formation of the terraces as they are made of travertine (a form of limestone), which is a sedimentary rock that is deposited by the hot water. The water temperature in this area is, on average, around 36 degrees Celcius and is enriched with a number of different minerals. The presence of different minerals effects the colour of the travertine which can also be red, tan or cream in colour but when free of impurities it is white. The mineral rich water leaves the springs, and flows down over the terraces. As it does so, the minerals in the water react with the oxygen in the air and carbon dioxide is produced and released and this degassing of the carbon dioxide leads to the deposition of calcium carbonate. Evaporation then leaves behind the calcium carbonate and other minerals which harden into a chalk-like sinter. This calcium carbonate accumulates everywhere, covering every surface, stone and rocky slope in reach. Therefore, layer by layer, the landscape around the hot springs has whitened and hardened and the terraces, themselves, are continually resculpted by the warm subterranean springs that seep through the surface.

No comments:

Post a Comment