cratons (IMAGE) Penn State Caption These ancient metamorphic rocks called gneisses, found on the Arctic Coast, represent the roots of the continents now exposed at the surface. The scientists said sedimentary rocks interlayered in these types of rocks would provide a heat engine for stabilizing the continents. Credit Jesse Reimink Usage Restrictions Credit must be given to the creator. Only noncommercial uses of the work are permitted. No derivatives or adaptations of the work are permitted. License CC BY-NC-ND 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.