Before revision: First, after 12,900 calendar years ago, smectite-rich sediments from the Missouri River drainage are progressively and quickly replaced by sediments , which are associated with the Great Lakes region and further south along the Mississippi River, as indicated by their clay mineralogy.
After revision: First, after 12,900 calendar years ago, smectite-rich sediments from the Missouri River drainage are progressively and quickly replaced by sediments associated with the Great Lakes region and further south along the Mississippi River, as indicated by their clay mineralogy.