The Austin Chalk formation
Geology, footprint, and mineral-owner context for the Austin Chalk, 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 Austin Chalk?
The Austin Chalk is an Upper Cretaceous fractured chalk that overlies the Eagle Ford from South and Central Texas into the Tuscaloosa trend of Louisiana. It was one of the earliest horizontal plays in the country, developed in the Pearsall and Giddings fields, and it has seen a recent revival as operators redrill it with longer laterals. USGS assessments of the Gulf Coast describe the play's undiscovered, technically recoverable resource as a play-wide figure, not a per-acre yield.
The Austin Chalk is a hard, naturally fractured carbonate that sits directly above the Eagle Ford across a long arc from South and Central Texas eastward into Louisiana. Because production depends on natural fractures, results vary a great deal from tract to tract, which made the chalk one of the first formations operators learned to drill horizontally, in the Pearsall field in the 1970s and the Giddings field through the 1980s and 1990s. Many Austin Chalk tracts also have Eagle Ford pay beneath them, so a single section of minerals can carry two stacked targets. The play has been revived recently with longer laterals and modern completions, and it extends east into the Tuscaloosa trend of Louisiana. For a mineral owner, an Austin Chalk royalty is valued on the income the wells actually pay, on the standard income multiple, not on any play-wide resource number.
Austin Chalk geology
- Age and lithology
- Upper Cretaceous naturally fractured chalk and marl, a carbonate reservoir whose production depends heavily on fracture networks. Source: USGS Gulf Coast assessment and the Texas Bureau of Economic Geology.
- Stacked over the Eagle Ford
- The Austin Chalk overlies the Eagle Ford, so many tracts carry both intervals as separate targets.
- Where it produces
- A long trend from South and Central Texas, including the Pearsall and Giddings fields, eastward into the Tuscaloosa trend of Louisiana.
How much oil and gas the Austin Chalk holds
The USGS has assessed the Austin Chalk and associated Upper Cretaceous reservoirs as part of its Gulf Coast assessment work, which reports undiscovered, technically recoverable oil and gas across the trend. The reported figures are undiscovered play-wide estimates, not proven reserves and not a measure of any individual property.
Source: USGS Gulf Coast assessment; Texas Bureau of Economic Geology.
Counties in the Austin Chalk play
These are the counties and parishes we cover where the Austin Chalk produces. Each links to local value context and the operators active there.
What the Austin Chalk 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 Austin Chalk is part of the Eagle Ford Shale. For the basin-wide value bands and the counties we buy in, see the Eagle Ford Shale page.
Austin Chalk questions
- What is the Austin Chalk?
- The Austin Chalk is an Upper Cretaceous fractured chalk that overlies the Eagle Ford from South and Central Texas into the Tuscaloosa trend of Louisiana. It was one of the earliest horizontal plays, developed in the Pearsall and Giddings fields, and has been revived recently with longer laterals.
- Why do Austin Chalk results vary so much?
- The Austin Chalk produces from natural fractures, so two nearby tracts can perform very differently depending on the fracture network each well intersects. Many tracts also have Eagle Ford pay beneath them, which can add a second stacked target.
- How are Austin Chalk minerals valued?
- An Austin Chalk interest is valued on the income it pays, roughly 36 to 72 times your average monthly royalty check. USGS resource figures describe the whole trend, not your property. This is an estimate, subject to verification, not an offer.
Sources
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