... 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 sedimentar...

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• Grade Level: High School