The Tuscaloosa Marine Shale is a 90-million-year-old

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...

formation across the

Gulf Coast The Gulf Coast of the United States, also known as the Gulf South, is the coastline along the Southern United States where they meet the Gulf of Mexico. The coastal states that have a shoreline on the Gulf of Mexico are Texas, Louisiana, Mississ ...

region of the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

. It is similar in composition and

geological age The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronol ...

to the

Eagle Ford Shale The Eagle Ford Group (also called the Eagle Ford Shale) is a sedimentary rock formation deposited during the Cenomanian and Turonian ages of the Late Cretaceous over much of the modern-day state of Texas. The Eagle Ford is predominantly compos ...

formation in southern

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

.Durham, L. S. (2011a
''Similar in age and lithology to Eagle Ford Tuscaloosa Another Shale Playground.''
AAPG Explorer, August 2011. The thickness of the formation varies from 500–800 feet, and is located at a depth of 11,000-15,000 feet.

Petroleum

The formation is an unconventional oil reservoir, meaning that a majority of the petroleum hydrocarbons (

crude oil Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crude ...

and

natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...

) originating in the source rock formations have not migrated out of the source rock, requiring advanced

horizontal drilling Directional drilling (or slant drilling) is the practice of drilling non-vertical bores. It can be broken down into four main groups: oilfield directional drilling, utility installation directional drilling, directional boring (horizontal dir ...

and

hydraulic fracturing Fracking (also known as hydraulic fracturing, hydrofracturing, or hydrofracking) is a well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid. The process involves the high-pressure injection of "frack ...

(fracking) technologies to reach economic viability for extraction. The potential reserve is currently estimated at 7 billion

barrels A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, u ...

of oil.Chacko J. J., B. L. Jones, J. E. Moncrief, R. Bourgeois, and B. J. Harder (1997
''An Unproven Unconventional Seven Billion Barrel Oil Resource - the Tuscaloosa Marine Shale.''
LSU Basin Research Institute Bulletin. vol. 7, pp. 1-22. {{Clear Cretaceous System of North America Shale formations of the United States Oil fields of the United States Cretaceous Louisiana Cretaceous Mississippi Cretaceous geology of Texas