Utica Shale

Utica Shale, a layer of rock below Marcellus Shale is quickly developing into a source of natural gas.

Utica Shale is a rock unit located a few thousand feet below Marcellus. It has the potential to become an enormous natural gas resource. Utica Shale is thicker than Marcellus, is more geographically extensive and is proving its ability to support commercial production.

Utica Shale has not been thoroughly examined however and it is unclear how it will respond to horizontal drilling and hydraulic fracking.

Source: http://geology.com/articles/utica-shale/