Branching Tree (IMAGE) Swansea University Caption This is a branching tree of cracks created naturally by injecting air into wet sand 1. Credit Campbell, Ozturk, & Sandnes (2017). <i>Physical Review Applied</i> Usage Restrictions None 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.