Crust formation Cartoon (IMAGE) University of Texas at Austin Caption A cartoon illustrating different modes of crust formation in the lower oceanic crust. Panel A shows the Gabbro Glacier model. Panel B shows the Sheeted Sills model. Credit Kathrin Faak, Laurence Coogan, Sumit Chakraborty. Usage Restrictions Include image 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.