On October tenth and eleventh I went on a field trip with the Snow College Geology FieldStudies class. One of the stops we made on the tenth was to the Dugway Geode Beds in Juab County. We drove a couple of miles into the beds to find a promising pit, then started searching and digging for geodes. It was a very successful trip and we all took home several geodes. Finding these beautiful crystal-filled rocks made me curious about how they form.
I found out that they form in two different ways. They can form in sedimentary rocks when organic matter such as a tree root, rots away and leaves a cavity in the ground. If the cavity is still preserved in the ground after the sediment becomes rock, it has the potential to become a geode. (Baggaley, 2012) To become a geode, water has to find its way into the cavity of the rock to deposit the minerals that are necessary to create crystals. After millions of years of mineral rich ground water running through tiny cracks in the rock, crystals will form in the cavity.
Baggaley, Kate. "Where Do Geodes Come From?" Scienceline. 20 Nov. 2012. Web. 23 Oct. 2014 http://scienceline.org/2012/11/where-do-geodes-come-from/
Ege, Carl. "Dugway Geodes - Utah Geological Survey." Dugway Geodes - Utah Geological Survey. Web. 23 Oct. 2014. http://geology.utah.gov/utahgeo/rockmineral/collecting/rkhd0500.htm