Illustration of plate tectonics (IMAGE) University of Texas at Austin Caption An artistic cross section of the Earth’s outer shell showing the effect of plate tectonics on the surface. Volcanoes form above the place where plates slide – or subduct – over one another. Credit Eirini Poulaki, The University of Texas at Austin Usage Restrictions Please credit creator License Original 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.