The Appalachian Basin's Marcellus shale holds the promise to become a top producing shale reservoir. It covers a vast area-many times larger than any other shale play--and exhibits excellent reservoir qualities. Recent strong well results show that the Marcellus is living up to its promise, and its location in the core of North America's premium natural-gas markets gives it leverage over more distant supplies. Find out the latest in this inclusive compilation. Includes two-page map in the publication.