Imatra Rapids (IMAGE) University of Helsinki Caption Imatra rapids emerged after the ice age. The traces of flowing water are still to be seen in the canyon. Credit Photo: Tapani Tolvanen Usage Restrictions Credit: Tapani Tolvanen 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.