#band-e-amir

There are no highly-detailed geologic maps of this area due to ongoing conflict in the region, but general maps show that the surrounding rocks are lightly metamorphosed, Paleozoic aged sedimentary rocks – the same sort of rocks found in mountains all over this area. Hundreds of millions of years ago, the area between the supercontinent Gondwana and the continental slivers that would come together to make Asia was dominated by a tongue of the ocean known as the Tethys Seaway. The tropical edges of that seaway became places where thick sequences of limestone were deposited, creating rocks found today throughout southern and southeast Asia. About 60 million years ago, India began colliding with Asia, eventually pushing the ancient sedimentary rocks up into the mountains seen here. The forces of erosion then began to work, cutting canyons like this one into the ancient sediments. The last ingredient in these lakes is travertine, a form of calcium carbonate. As groundwater flowed through the ancient limestones, some of it dissolved. In the ground, a balance between the surrounding rocks and the chemistry of the water is maintained, but if the water moves out of the ground that balance is offset. These limestones have been fractured as a result of the mountain building, creating paths that water can flow through to create springs. When the water exits the ground from those springs, it enters the lake and the chemistry changes, causing the calcium carbonate to precipitate as travertine. This travertine has created dams that separate the six lakes and hold the water calm in these spots. Apparently this calm is occasionally disturbed as the local population uses the ample supply of grenades that have gone into Afghanistan in recent decades to fish, exploding them underwater and then gathering the fish killed by the shock. -JBB Image credit: https://commons.wikimedia.org/wiki/File:Afghanistan%27s_Grand_Canyon.jpg Reference: https://earthobservatory.nasa.gov/images/38311/band-e-amir-national-park-afghanistan http://news.bbc.co.uk/2/hi/south_asia/8013017.stm