The Arcadia Park Shale is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

within the

Eagle Ford Group The Eagle Ford Group (also called the Eagle Ford Shale) is a Sedimentary rock, 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 pr ...

that

outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth and other terrestrial planets. Features Outcrops do not cover the majority of the Earth's land surface because in most p ...

s in the northern portion of

East Texas East Texas is a broadly defined cultural, geographic, and ecological region in the eastern part of the U.S. state of Texas that consists of approximately 38 counties. It is roughly divided into Northeast Texas, Northeast, Southeast Texas, Sout ...

. It was deposited during the Middle to Late

Turonian The Turonian is, in the International Commission on Stratigraphy, ICS' geologic timescale, the second age (geology), age in the Late Cretaceous epoch (geology), Epoch, or a stage (stratigraphy), stage in the Upper Cretaceous series (stratigraphy), ...

of the Late

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

.Denne, R. A., Breyer, J. A., Callender, A. D., Hinote, R. E., Kariminia, M., Kosanke, T. H., Kita, Z., Lees, J. A., Rowe, H., Spaw, J. M., and Tur, N. (2016) Biostratigraphic and geochemical constraints on the stratigraphy and depositional environments of the Eagle Ford and Woodbine Groups of Texas: ''in'' Breyer, J. A. (ed.), The Eagle Ford Shale: A renaissance in U.S. oil production, AAPG Memoir 110, p. 1-86. It was originally described by W. L. Moreman from

s near the former Arcadia Park railway station west of downtown

Dallas Dallas () is a city in the U.S. state of Texas and the most populous city in the Dallas–Fort Worth metroplex, the List of Texas metropolitan areas, most populous metropolitan area in Texas and the Metropolitan statistical area, fourth-most ...

, where it is 100 ft (30 m) thick. In the type area there is an

unconformity An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval ...

between the Arcadia Park and the underlying

Britton Formation The Britton Formation is a geologic formation deposited during the Middle Cenomanian to the Early Turonian ages of the Late Cretaceous in modern-day East Texas. It forms the lower half of the Eagle Ford Group in the northern portion of East Texa ...

. The base of the Arcadia Park is a thin

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

termed the Kamp Ranch Limestone. The Kamp Ranch Limestone is made up of broken pieces (prisms) of ''

Inoceramus ''Inoceramus'' (Greek: translation "fibrous shell" for the fibrous structure of the mineral crystals in the shell) is an extinct genus of fossil marine pteriomorphian bivalves that superficially resembled the related winged pearly oysters of th ...

'' clams, and also contains

shark Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...

's teeth. The remainder of the Arcadia Park in the

area is

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

with

concretion A concretion is a hard and compact mass formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular shapes a ...

Sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

s are found within the Arcadia Park north of

. The

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

s have been termed the Bells Sandstone Member for

s in Grayson County, and the Sub-Clarksville Sandstone in the subsurface. The shale overlying the Bells Sandstone has been named the Maribel Shale

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s that occur in the Arcadia Park include

's teeth and other

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

remains,

ammonite Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...

inoceramid The Inoceramidae are an extinct family (biology), family of bivalves ("clams") in the Class Mollusca. Fossils of inoceramids are found in marine sediments of Permian to latest Cretaceous in age. Inoceramids tended to live in upper bathyal and ner ...

clams,

oyster Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but no ...

s, and

foraminifera Foraminifera ( ; Latin for "hole bearers"; informally called "forams") are unicellular organism, single-celled organisms, members of a phylum or class (biology), class of Rhizarian protists characterized by streaming granular Ectoplasm (cell bio ...

. The Sub-Clarksville Sandstone is a conventional source of

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) and lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturate ...

production in

.Wood, D. H., and A. B Giles (1982) Hydrocarbon accumulation patterns in the East Texas salt dome province: Bureau of Economic Geology Geological Circular 82-6, 36 p.

References

{{Clear Shale formations of the United States Cretaceous geology of Texas Turonian Stage

See also

References