Menominee Crack Diagram (IMAGE) Michigan Technological University Caption This cross section reveals how the thin layer of clay deformed on top of the brittle limestone that broke into a pop-up structure. Credit Michigan Tech, Ian Repp Usage Restrictions please credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.