The Marcellus Shale is referred to as an unconventional source of natural gas because of the way natural gas
is trapped within the rock. Conventional sources of natural gas are often found in permeable, porous rocks
(like sandstones), where natural gas or oil flows toward an area of lower pressure and eventually can consolidate
the resource in ‘pools’ or ‘pockets.’ Extracting conventional resources requires locating a pocket and removing the oil or gas