A "frenzy unlike any seen in decades is unfolding here in rural Pennsylvania," according to the New York Times. The source of the excitement is gas. Drillers have known for some time that the Marcellus Shale formation (see map above) has natural gas, but they didn't have the techniques to get it out of the ground.Now they think they do and there are meetings across the region with land agents leasing up rights to the fuel. One academic figures that 20 oil and gas companies will invest $700 million this year developing the Marcellus Shale, half of that in Pennsylvania.The shale is drilled horizontally, using techniques developed in Texas. There are horizontal wells now under the city of Fort Worth. The Marcellus, however, is much larger than similar fields in Texas.