The Marcellus and Other Shale Plays in Pennsylvania: Are They Really Worth All the Fuss? The actual value of the Marcellus as a gas reservoir has yet to be firmly established, says John Harper, chief, geological division of the Pennsylvania Geological Survey. “The Marcellus was not considered promising until gas prices increased and [drilling] technology advanced,” Harper says. “But only time will tell just how lucrative the Marceulls play truly will be.” Harper will discuss this at 4 p.m., Monday, April 27 in this, the final talk of the 2009 Spring Series of Earth Talks related to Pennsylvania's Marcellus Shale Play. (Javascript is required to view Mediasite content)