Undular Bore (IMAGE) University at Buffalo Caption Undular bore and whelps near the mouth of Araguari River, Brazil. Credit Credit: USGS/Susan Bartsch-Winkler and David K. Lynch, via Wikimedia Commons: https://commons.wikimedia.org/wiki/File:Undular_bore_Araguari_River-Brazil-USGS-bws00026.jpg Usage Restrictions This image must be credited to USGS/Susan Bartsch-Winkler and David K. Lynch, via Wikimedia Commons: https://commons.wikimedia.org/wiki/File:Undular_bore_Araguari_River-Brazil-USGS-bws00026.jpg 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.