The Marcellus formation
Geology, footprint, and mineral-owner context for the Marcellus, drawn from public USGS and state survey sources. Resource figures describe the play as a whole and are not a per-acre value. Every figure on this page is an estimate subject to verification of your specific interest.
Last updated June 2026.
What is the Marcellus?
The Marcellus is the Middle Devonian organic-rich shale of the Appalachian Basin and the largest natural gas field in the United States by production, with a dry-gas core in northeastern Pennsylvania and wet gas in southwestern Pennsylvania and northern West Virginia.
The Marcellus is the largest natural gas field in the United States by production. It is a Middle Devonian organic-rich black shale that blankets much of the Appalachian Basin, and it transformed the region into the country's leading gas supplier. The play has two main character zones: a prolific dry-gas core in northeastern Pennsylvania, in Susquehanna and Bradford counties, and a wet-gas and liquids-rich area in southwestern Pennsylvania and northern West Virginia. Across much of the basin the Marcellus sits above the deeper Utica and Point Pleasant interval, so a single tract can hold stacked rights. For a mineral owner, a Marcellus royalty is typically a substantial, gas-weighted income stream, valued on the standard income multiple applied to the checks your wells actually pay, with gas prices and the dry-versus-wet gas mix influencing where it lands in the range.
Marcellus geology
- Age and lithology
- Middle Devonian organic-rich black shale, a prolific gas source and reservoir across much of the Appalachian Basin. Source: USGS Appalachian Basin Province assessment and Pennsylvania Geological Survey.
- Above the Utica
- The Marcellus sits above the deeper Ordovician Utica and Point Pleasant interval across much of the basin, so a tract can hold stacked rights in more than one interval.
- Where it produces
- Dry-gas core in northeastern Pennsylvania (Susquehanna, Bradford); wet gas in southwestern Pennsylvania and northern West Virginia, and into eastern Ohio.
How much oil and gas the Marcellus holds
In 2019 the USGS assessed the Marcellus Shale of the Appalachian Basin and reported a mean of about 97 trillion cubic feet of undiscovered, technically recoverable natural gas, along with associated natural gas liquids. This is an undiscovered play-wide estimate, not proven reserves and not a measure of any individual property.
Source: USGS Fact Sheet 2019-3061 (Marcellus Shale and Point Pleasant-Utica, Appalachian Basin, 2019 assessment).
What the Marcellus means for your minerals
A resource estimate for a play is not the value of your acreage. Your mineral and royalty interest is valued on the income your wells actually pay, roughly 36 to 72 times your average monthly royalty check, the same as 3 to 6 times your annual royalty. Where you land in that band depends on your wells decline, the operator, your royalty rate, and any undeveloped drilling upside. For the full method and a free on-screen estimate, see what are my mineral rights worth.
The Marcellus is part of the Appalachian Basin. For the basin-wide value bands and the counties we buy in, see the Appalachian Basin page.
Marcellus questions
- What is the Marcellus formation?
- The Marcellus is a Middle Devonian organic-rich shale in the Appalachian Basin and the largest natural gas field in the United States by production. Its dry-gas core is in northeastern Pennsylvania, with wet gas in southwestern Pennsylvania and northern West Virginia.
- How big is the Marcellus resource?
- In 2019 the USGS reported a mean of about 97 trillion cubic feet of undiscovered, technically recoverable natural gas for the Marcellus. That is an undiscovered play-wide figure for the whole basin, not proven reserves and not a measure of any one property.
- How are Marcellus minerals valued?
- A Marcellus interest is valued on the income it pays, roughly 36 to 72 times your average monthly royalty check, with gas prices and the dry-versus-wet gas mix affecting the range. USGS resource figures describe the whole play, not your property. This is an estimate, subject to verification, not an offer.
Sources
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