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| | Photos: Jordanie: Roches de Petra / Jordan: Petra Rocks / 2005 |
 | | Petra is one of the world's most beautiful architectural sites carved from some of the oldest exposed sandstone on Earth (Cambrian and Ordovician sanstone that is 450-550 million years old). |
 | | However, the sandstone in Petra is typical in that it is comprised of colorless quartz clasts (the particles in sandstone) attached by a matrix binding that is composed of silica (Si), calcium (Ca), iron (Fe), aluminum (Al), manganese (Mn) and minor amounts of others (sodium (Na), lithium (Li), etc.). |
 | | He has shown that Petra structures, which have been stable since their creation two thousand years ago, are deteriorating at an accelerated rate due to natural and human-induced stone decay processes, most notably due to increasing regional and global tourism. |
| www.pa-chouvy.org /Photos/Jordanie/JordaniePetraRoches.htm (424 words) |
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