Geology and history of Senatorial Cave in Austin, Texas explored.

Senatorial Cave is one of the lesser known caves of Austin, Texas. Only cavers and spelunkers know about this cave. This news article will explore the geology, history, and wildlife of Senatorial Cave. That is what news article is going to be about. Senatorial Cave is also known as Senatorial Sink Cave.


Senatorial Cave opens to an entrance room that ends into a rocky pit. The entrance room descends to the main level of the cave. There is fine silt on some areas of the floor. The inside has underhanging walls. Now this area has a constant 100 percent humidity and total darkness. Live Oak Cave and Senatorial Sink are located east of Get Down Cave and Senatorial Cave. (Ref: https://repositories.lib.utexas.edu/bitstream/handle/2152/22314/Perrone-2008.pdf?sequence=2)

Senatorial Cave is located in the drainage base beside Senatorial Sink. Senatorial Cave is a small but important cave that is used to recharge the Edwards Aquifer. There is good quality water confirmed to be flowing over Equinox Cave and Senatorial Cave. This cave extends below Senatorial Sink and forms a direct connection to the aquifer. (Ref: https://repositories.lib.utexas.edu/bitstream/handle/2152/22314/Perrone-2008.pdf?sequence=2)

Senatorial Cave is a large solution sinkhole with a large bowl inside which is part of the  drainage  system that exists at the base of any sinkhole of the Circle C Ranch and Circle C neighborhood. This enclosed sinkhole is located within Edwards Aquifer. Senatorial Sink is bowl shaped. The setback distance of this sink is 75 feet. (Ref: https://citeseerx.ist.psu.edu/viewdoc/download;jsessionid=F2A679B4B237FCBCAD71D8C14A0BD58E?doi=10.1.1.692.9179&rep=rep1&type=pdf)

Limestone ridge can be seen at the fence. The fence outlines the boundary of Senatorial Sink. The most common minerals in this environment, carbonates, include the common and sometimes clear mineral calcite. The limestone rocks of the Edwards Aquifer group were originally deposited about 100 million years ago when a warm, shallow sea covered central Texas. Marine life flourished. (Ref: https://repositories.lib.utexas.edu/bitstream/handle/2152/22314/Perrone-2008.pdf?sequence=2)

Senatorial Cave is located in a preserve called Western Oaks Karst Preserve with karst features such as Equinox Cave, Live Oak Cave, and Survey Line Cave. Here Senatorial Cave is an example of a swallet that (prior to gating) could absorb much of the creek flow that occurs after rain. Water is visible only for short periods after rain.

There is a reason why Senatorial Cave is gated. Senatorial Cave is gated as this cave is located in the environmentally sensitive Edwards Aquifer. TCMA installed a perimeter fence at the entrance to restrict access. (Ref: https://www.researchgate.net/publication/263425729_Edwards_Aquifer_hydrogeology)

Horsemint has a distinctive citrus or lemony scent when the leaves are rubbed or crushed. It is very easy to grow and often forms large colonies. Bees and butterflies are attracted to this plant. Each whorl in the elongated spike is subtended by whitish or lavender, leaf-like bracts. Several stems grow from the base and are lined with pairs of lance-shaped leaves. (Ref: https://www.wildflower.org/plants/result.php?id_plant=MOCI&fbclid=IwAR1SMgdk6xVacW1MATpW2T0y7xGrfsUTMQqCpitKdxarGYaCp4ZHE9er0HU)


Here is the history of Senatorial Cave.

Senatorial Cave was formed 100 million years ago when there were many karst features were extant in several spacious caves. The limestone rocks of the Edwards Aquifer were originally deposited when a warm, shallow sea covered central Texas where Marine life flourished. As the marine organisms died, their calcium carbonate shells and skeletons sank and solidified into layers of limestone. The sea level lowered and the Edwards limestone was buried and then uplifted. A sink called Senatorial Cave was formed by the collapse of what was once a much larger cave. This collapse was many years ago and now dirt has fallen into the sink. Here Senatorial Cave is a small part of the original larger cave that did not collapse and now consists of a passage that opens into a low room beside the sink. (Ref: https://repositories.lib.utexas.edu/bitstream/handle/2152/22314/Perrone-2008.pdf?sequence=2)

Senatorial Cave was discovered by surveyors during the early development of the Circle C neighborhood in 1986. Senatorial Sink was privately owned then and located on the Circle C Ranch property. Senatorial Cave was named for the impressive live oak trees around the cave area.

Texas Cave Management Association (TCMA) partnered up with local developer, Lumberman's Investment Corp., for a proposed cave preserve at the Village of Western Oaks in 1998. The preserve would include Get Down Cave, Equinox Cave, Live Oak Cave, Survey Line Cave, and Senatorial Sink (Senatorial Sink Cave). Mike Warton gated all 5 caves in 1999. A management plan was developed for the preserve as coordinated by the City of Austin in 1999. This allowed plans to go forward. Mike Warton gated Senatorial Cave in 1999 with a few other caves.

However due to the lack cave management on of the part of the city and developer, it took nearly 8 years to gain full ownership, land rights, and mineral rights to the preserve. TMCA expressed an interest in owning and managing the preserve many years in advance as they had been the de facto managers for 7½ years.

Western Oaks Karst Preserve would open to the public in 2005. TCMA members would give guided tours of Get Down Cave along with the other caves starting in 2006. (Ref: www.bseacd.org/western_oaks)

BCP staff repaired the perimeter fence around Senatorial Cave in 2018 due to the cave being located in the Recharge Zone of Edwards Aquifer. After the perimeter fence around Senatorial Sink was repaired, BCP staff continued to collect soft ticks from this sink in an effort to collaborate with Texas State University researchers and Baylor University researchers whom  are trying to determine more information about tick borne relapsing fever (TBRF). (Ref: https://digital.lib.usf.edu/SFS0070259/00001)

Today Senatorial Sink is located in a preserve called Western Oaks Karst Preserve with karst features such as Equinox Cave, Live Oak Cave, and Survey Line Cave. Senatorial Sink is gated as this sinkhole is located in the environmentally sensitive Edwards Aquifer. TCMA installed a perimeter fence at the entrance to restrict access. Texas Cave Management Association has been managing this cave for close to 15 years. (Ref: https://www.researchgate.net/publication/263425729_Edwards_Aquifer_hydrogeology)


Senatorial Cave is located at 5402 Davis Lane, Austin, Texas, US 78749.