Sedimentary rocks, Mackenzie River. (IMAGE) University of Oxford Caption Sedimentary rocks on the banks of the Mackenzie River, Canada, a major river basin where rock weathering is a CO2 source. Image credit: Robert Hilton. Credit Robert Hilton. Usage Restrictions The image can be used if credited. 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.