Mid-ocean Ridges (IMAGE) University of Oregon Caption Colored and black points mark the global distribution of mid-ocean ridges, with ages of 66 million years ago created at spreading rates above and below 35 millimeters a year, respectively. Colors indicate the maximum gravity anomaly within 2 degrees. Credit Courtesy of Joseph Byrnes Usage Restrictions Use credit 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.