Chert Nodules in the Keeler Canyon Formation
Chert Nodules in the Keeler Canyon Formation. These nodules of microcrystalline silicon dioxide, embedded here in limestone of Pennsylvanian age, formed as concretions in soft carbonate-rich sediments. They grew from silica dissolved in ground water. Similar chert nodules are found in many Paleozoic limestones and dolomites around the world. Marble Canyon. Cottonwood Mountains. Death Valley National Park. Inyo Co., Calif.