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Iowa natural history

 

            
            
             My trip to the Iowa Historical Museum included a fascinating journey through Iowa's geological as well as natural history. I started at the geological exhibits and learned that the geode is the state rock. Geodes are unique mineral objects within a rock layer of different composition. It was declared the state rock in 1967by the Iowa General Assembly. Geodes are very interesting in how they are made the following is a very good explanation that I found on the internet.
             How Geodes Are Created.
             "Geodes begin as bubbles in volcanic rock or as animal burrows, tree roots or mud balls in sedimentary rock. Over time, the outer shell of the spherical shape hardens, and water containing silica precipitation forms on the inside walls of the hollow cavity within the geode. The silica precipitation can contain any variety of dissolved minerals; the most common being quartz, but amethyst and calcite are also found. Over a period of thousands of years, layers of silica cool, forming crystals of different minerals within the cavity. Different types of silica cool at varying temperatures, thus creating layers of different types of mineral crystals." (http://www.desertusa.com/magjan98/jan_pap/du_rock_geode.html).
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             Other Geological Findings From My Adventures.
             Iowa soil and rock has formed over millions of years of geological processes. They have been formed in times that most would never suspect that the land of Iowa has went through. Such as, our rich top soil come from the glacier movements that Iowa experienced during the Ice Age. The limestone comes from a time when Iowa was covered in sea water and was nothing but as sea floor for the world (hard to imagine). The coal that is here was produced from the time when it was swamp land, I wonder if there are any remnants of alligators from ancient times or if reptilians even existed then. The shallow seas of the Paleozoic era represented a great changing age for this land.


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