On quartzite (IMAGE) Penn State Caption A typical stand of chestnut oaks growing on top of the Tuscarora Quartzite formation in Rothrock State Forest. Forests growing above sandstone bedrock like this have smaller trees and less diversity of tree species. Credit Warren Reed, Penn State Usage Restrictions non commercial use only 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.