Tesnus is a

ghost town Ghost Town(s) or Ghosttown may refer to: * Ghost town, a town that has been abandoned Film and television * ''Ghost Town'' (1936 film), an American Western film by Harry L. Fraser * ''Ghost Town'' (1956 film), an American Western film by All ...

and

unincorporated community An unincorporated area is a region that is not governed by a local municipal corporation. Widespread unincorporated communities and areas are a distinguishing feature of the United States and Canada. Most other countries of the world either hav ...

Brewster County Brewster County is a county located in the U.S. state of Texas. It is in West Texas and its county seat (and only city) is Alpine. It is one of the nine counties that comprise the Trans-Pecos region, and borders Mexico. Brewster County is t ...

, in the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sove ...

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 ...

History

Tesnus was laid out in 1882 when the

Southern Pacific Railroad The Southern Pacific (or Espee from the railroad initials- SP) was an American Railroad classes#Class I, Class I Rail transport, railroad network that existed from 1865 to 1996 and operated largely in the Western United States. The system was ...

was extended to that point. Tesnus (sunset spelled backwards) was so named for the fact a

sunset Sunset, also known as sundown, is the daily disappearance of the Sun below the horizon due to Earth's rotation. As viewed from everywhere on Earth (except the North and South poles), the equinox Sun sets due west at the moment of both the spr ...

appeared in the logo of the Southern Pacific Railroad. A post office was established at Tesnus in 1912, and remained in operation until 1954.

Geology

Tesnus, Texas, is the namesake for the

geological 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 expo ...

known either as the Tesnus Formation or Tesnus Shale.

Bedrock In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface material. An exposed portion of be ...

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

s around Tesnus, Texas serve as the type location for the Tesnus Formation.Baker, C.L. and Bowman, W.F., 1917. ''Geologic exploration of the southeastern front range of Trans-Pecos Texas.'' ''University of Texas Bulletin''. 1753, 117 pp. The Upper

Mississippian Mississippian may refer to: * Mississippian (geology), a subperiod of the Carboniferous period in the geologic timescale, roughly 360 to 325 million years ago *Mississippian culture, a culture of Native American mound-builders from 900 to 1500 AD ...

– Lower

Pennsylvanian Pennsylvanian may refer to: * A person or thing from Pennsylvania * Pennsylvanian (geology) The Pennsylvanian ( , also known as Upper Carboniferous or Late Carboniferous) is, in the International Commission on Stratigraphy, ICS geologic timesca ...

Tesnus Formation is a significant, wide-spread formation that is composed primarily of interbedded olive-drab to black

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especia ...

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, ...

, and fine- to very fine-grained

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

. It thins from in the eastern

Marathon Uplift The Marathon Uplift is a Paleogene-age domal uplift, approximately in diameter, in southwest Texas. The Marathon Basin was created by erosion of Cretaceous and younger strata from the crest of the uplift.McBride, E.F. and Hayward, O.T., 1988''G ...

westward to . The base of the Tesnus Formation in the eastern Marathon Uplift consists of a thick shale blanket that makes up the entire thickness of this formation in the west. The sandstone layers are as much as thick, but most layers are between . Locally, its shales contain carbonaceous plant fragments and spores and some of its sandstone beds contain wood casts up to long. Rare fossils of

conodont Conodonts ( Greek ''kōnos'', " cone", + ''odont'', " tooth") are an extinct group of agnathan (jawless) vertebrates resembling eels, classified in the class Conodonta. For many years, they were known only from their tooth-like oral elements, w ...

radiolaria The Radiolaria, also called Radiozoa, are protozoa of diameter 0.1–0.2 mm that produce intricate mineral skeletons, typically with a central capsule dividing the cell into the inner and outer portions of endoplasm and ectoplasm. The elab ...

sponge spicule Spicules are structural elements found in most sponges. The meshing of many spicules serves as the sponge's skeleton and thus it provides structural support and potentially defense against predators. Sponge spicules are made of calcium carbon ...

s, a

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...

, and inarticulate

brachiopod Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, ...

s have also been found in the Tesnus Formation.McBride, E. F., 1989, ''Stratigraphy and sedimentary history of pre-Permian Paleozoic rocks of the Marathon uplift'', in R. D. Hatcher, Jr., W. A. Thomas, and G. W. Viele, eds., ''The Appalachian-Ouachita orogene in the United States: the geology of North America'': Boulder, Colorado, Geological Society of America, v. F-2, pp.603–620. The sediments comprising the Tesnus Formation accumulated within deep sea

submarine fan Abyssal fans, also known as deep-sea fans, underwater deltas, and submarine fans, are underwater geological structures associated with large-scale sediment deposition and formed by turbidity currents. They can be thought of as an underwater ve ...

and channel complexes. These sediments came dominantly from the southeast, likely from an approaching continental

terrane In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its ow ...

that later collided with North America during the

Ouachita orogeny The Ouachita orogeny was a mountain-building event that resulted in the folding and faulting of strata currently exposed in the Ouachita Mountains. The more extensive Ouachita system extends from the current range in Arkansas and Oklahoma so ...

. The Tesnus Formation and associated strata were folded into a northeast trending

fold belt Fold, folding or foldable may refer to: Arts, entertainment, and media * ''Fold'' (album), the debut release by Australian rock band Epicure * Fold (poker), in the game of poker, to discard one's hand and forfeit interest in the current pot * Abo ...

and

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If ...

ed northwestward by the Ouachita orogeny, which also formed the

Ouachita Mountains The Ouachita Mountains (), simply referred to as the Ouachitas, are a mountain range in western Arkansas and southeastern Oklahoma. They are formed by a thick succession of highly deformed Paleozoic strata constituting the Ouachita Fold and Thr ...

Arkansas Arkansas ( ) is a landlocked state in the South Central United States. It is bordered by Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, and Texas and Oklahoma to the west. Its name is from the ...

and Oklahoma.McBride, E.F. and Hayward, O.T., 1988
''Geology of the Marathon uplift, west Texas.''
''Geological Society of America Centennial Field Guide'', 4, pp.411-416.Hickman, R.G., Varga, R.J., and Altany, R.M., 2009, ''Structural style of the Marathon thrust belt, West Texas.'' ''Journal of Structural Geology'', v. 31, no. 9, pp.900–909.

References

Unincorporated communities in Brewster County, Texas Unincorporated communities in Texas {{BrewsterCountyTX-geo-stub

History

Geology

See also

References