Depth Chart (IMAGE) Brown University Caption The geologic forces that shape the Earth's surface do their work in the lithosphere, often out of sight and far below the surface. Researchers have now measured the lithosphere’s thickness in southern California. It varies widely, from less than 25 miles to nearly 60 miles. Credit Fischer Lab, Brown University 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.