Ancient Lava Flows (IMAGE) Washington State University Caption The Grande Ronde lava flows created the largest mapped flood basalt on Earth. New research shows that its Wapshilla Ridge flow produced massive amounts of sulfur dioxide, obscuring the sun and cooling the planet. Credit WSU Usage Restrictions None 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.