Engelder (image) Penn State Share Print E-Mail Caption Dr. Terry Engelder, professor of geosciences, Penn State shows black shale with markings indicating fracturing. Credit Greg Grieco, Penn State Usage Restrictions with news release for informational use. Share Print E-Mail 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.