In addition, the Marcellus Shale was buried by numerous other rock layers in the last 400 million years,
some of which have been eroded since the Alleghanian Orogeny (in part by the numerous glaciations that have sculpted the current landscape of the Northeast). These erosional forces have brought the Marcellus Shale closer to the surface
of the Earth and thereby decreased the downward pressure provided by overlying rocks. As overlying weight
that had compressed the ground was released, much like a memory foam mattress, the decrease in pressure
resulted in the J3 joint set. They, too, run roughly parallel, and are referred to as release joints and unloading joints