The Texas Hill Country is a geographic region of Central and South Texas, forming the southeast part of the Edwards Plateau. Given its location, climate, terrain, and vegetation, the Hill Country can be considered the border between the American Southeast and Southwest. The region represents the very remote rural countryside of Central Texas, but also is home to growing suburban neighborhoods and affluent retirement communities.
The Balcones Fault or Balcones Fault Zone is an area of largely normal faulting in the U.S. state of Texas that runs roughly from the southwest part of the state near Del Rio to the north-central region near Dallas along Interstate 35. The Balcones Fault zone is made up of many smaller features, including normal faults, grabens, and horsts. One of the obvious features is the Mount Bonnell Fault.
The Edwards Plateau is a geographic region forming the crossroads of Central, South, and West Texas. It is bounded by the Balcones Fault to the south and east, the Llano Uplift and the Llano Estacado to the north, and the Pecos River and Chihuahuan Desert to the west. San Angelo, Austin, San Antonio, and Del Rio roughly outline the area. The southeast portion of the plateau is known as the Texas Hill Country.
The Alabama cave shrimp is a species of shrimp in the family Atyidae, found only in caves in the state of Alabama.
The Kentucky cave shrimp is an eyeless, troglobite shrimp. It lives in caves in Barren County, Edmonson County, Hart County and Warren County, Kentucky. The shrimp's shell has no pigment; the species is nearly transparent and closely resembles its nearest relative, the Alabama cave shrimp.
The fountain darter is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is found in the headwaters of only two rivers in Texas, United States: the Comal River and the San Marcos River. It is generally smaller than 3 cm (1.2 in) long and feeds on small invertebrates. It is a federally listed endangered species of the United States and is also listed as endangered by the IUCN.
The San Marcos River rises from the San Marcos Springs, the location of Aquarena Springs, in San Marcos, Texas. The springs are home to several threatened or endangered species, including the Texas blind salamander, fountain darter, and Texas wild rice. The river is a popular recreational area, and is frequented for tubing, canoeing, swimming, and fishing.
The Edwards Aquifer is one of the most prolific artesian aquifers in the world. Located on the eastern edge of the Edwards Plateau in the U.S. state of Texas, it is the source of drinking water for two million people, and is the primary water supply for agriculture and industry in the aquifer's region. Additionally, the Edwards Aquifer feeds the Comal and San Marcos Springs, provides springflow for recreational and downstream uses in the Nueces, San Antonio, Guadalupe, and San Marcos river basins, and is home to several unique and endangered species.
The Texas blind salamander is a rare and endangered cave-dwelling troglobite amphibian native to San Marcos, Hays County, Texas, specifically the San Marcos Pool of the Edwards Aquifer. This species resembles the olm, another stygofaunal salamander from Europe. Unlike the olm, this amphibian's body is not as elongated, and also has less reduced digits on its limbs.
San Marcos Springs is the second largest natural cluster of springs in Texas. The springs are located in the city of San Marcos, Texas, about 30 miles (48 km) southwest of Austin and 46 miles (74 km) northeast of San Antonio.
The vernal pool fairy shrimp, Branchinecta lynchi, is a species of freshwater crustacean in the family Branchinectidae. It is endemic to the U.S. states of Oregon and California, living in vernal pools as well as non-vernal pool habitat. They range in size from 0.43 to 0.98 inches long. Vernal pool fairy shrimp are listed as a vulnerable species on the IUCN Red List, and has been listed as Federally Threatened species since 1994.
Palaemon cummingi, known as the Squirrel Chimney Cave shrimp or the Florida cave shrimp, is a threatened species of cave-dwelling shrimp in the family Palaemonidae. P. cummingi has been observed in one sinkhole called Squirrel Chimney in Alachua County, Florida near Gainesville. Although exact numbers are unknown, it is speculated that the current P. cummingi population is very small.
Stygobromus balconis, the Balcones cave amphipod, is a troglomorphic species of amphipod in family Crangonyctidae. It is endemic to Texas in the United States.
Stygobromus pecki, the Peck's cave amphipod, is a rare species of crustacean found in four cavern areas of southwestern Texas in the United States. It is a federally listed endangered species in the United States and is also listed as Endangered on the IUCN Red List. Because of the species' limited geographical distribution, not much information on S. pecki is known. As of April 2022, there is no available 5-year review, Species Status Assessment, or recovery plan for the species. However, the Edwards' Aquifer Habitat Conservation Program (EAHCP), with the support of the U.S. Fish and Wildlife Service (UFWS), has been attempting to further study and promote conservation of S. pecki.
Wonder Cave is a show cave located in the Balcones Fault in San Marcos, Texas. Its entrance is one mile southwest of the county courthouse in San Marcos. The cave is reported to be the only commercially operated dry-formed cave in the United States. The fault itself is visible in the cave's ceiling. Originally named Bevers Cave after Mark Bevers, who discovered it in 1893, the cave for a while concealed Bevers' illicit distilling and gambling enterprises.
Balcones Canyonlands is a national wildlife refuge located in the Texas Hill Country to the northwest of Lago Vista, Texas. The refuge was formed in 1992 to conserve habitat for two endangered songbirds, the golden-cheeked warbler and the black-capped vireo, and to preserve Texas Hill Country habitat for numerous other wildlife species. The refuge augments a similarly named preserve in Austin called the Balcones Canyonlands Preserve.
Palaemon paludosus, coommonly known as ghost shrimp, glass shrimp, and eastern grass shrimp, is a species of freshwater shrimp from the southeastern United States.
Palaemon pugio, commonly known as daggerblade grass shrimp, is a small, transparent species of shrimp with yellow coloring and brownish spots. It can be found in estuarine and tidal marsh habitats throughout the western Atlantic Ocean and Gulf of Mexico. Palaemon pugio has a smooth carapace and abdomen, as well as three pairs of legs. The second pair is the strongest, while the third pair lacks chelae (claws). It reaches a length of around 5 cm (2.0 in), and has a life span of around one year. Like most grass shrimp, it is a forager and feeds on a variety of items, including microalgae. They themselves are consumed by killifish and other small foraging fish.
Palaemon kadiakensis, commonly known as the Mississippi grass shrimp, is a species of freshwater shrimp from the central United States, specifically the Mississippi River Basin.
