Concretion Exposed Pin

"Concretion Exposed" One of the most unusual landmarks in Theodore Roosevelt National Park's North Unit is the area called the Cannonball Concretions. For me, it was the most interesting place to spend some extra time to see and learn how on earth concretions grow. I condensed some information I read: As iron carbonate dissolves in groundwater, it forms around a fragment in the rock, such as a leaf, shell, bone, or fossil. The iron compound grows around this nucleus, and a concretion begins. As water and wind erode the calcite-bonded sandstone, the concretions appear in the forms of spheres, pipes, or irregular shapes that are often harder than the surrounding sedimentary rock. ©Debra Martz, All Rights Reserved 20250806-DSC_2849 AI Text