Wow! I’ve seen many photos of caves and visited a few over the years, but I can’t rememb
Wow! I’ve seen many photos of caves and visited a few over the years, but I can’t remember ever thinking that the wall outside of a cave looked as spectacular as this one. This gigantic wall of limestone is located in Phong Nha-Kẻ Bàng National Park in Vietnam and the tunnel is the entrance of an underground river flowing within Phong Nha Cave. It is part of one of the world’s largest complexes of limestone and was named a UNESCO world Heritage site in 2003. The caves and walls are the caused by a type of erosion that creates “karst” features. Karst weathering happens on rocks that can partially dissolve in water. Rainwater is slightly acidic due to carbon dioxide in the atmosphere; that acid causes exposed, soluble rocks to begin dissolving, forming low spots that concentrate additional water. As rains continue, the lows expand, eventually forming caves and sharp walls once enough rock has been eaten away. The rocks you see are Ordovician-aged limestones, about 400 million years old. Now, exposed in to the tropical rains of Vietnam and neighboring Laos, these rocks form one of the most spectacular karst provinces in the world. -JBB Image credit: Wikimediahttp://en.wikipedia.org/wiki/File:Phongnhakebang2.jpg Read more:http://whc.unesco.org/en/list/951http://www.esi.utexas.edu/outreach/caves/karst.php -- source link
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