- Special Hazards: Large shaft entrance, obscure guano miners'
entrances, and loose breakdown, especially near the Lake Room; see Special
Instructions for specific details.
- Length: 329 m (1,081 ft.)
- Depth: 107 m (351 ft.)
- Author:
George Veni
The general public is not allowed to enter the
cave, but may view the evening bat flight tours offered by the
Devil's Sinkhole Society (DSS). These tours are usually
offered from April through October depending on the presence of the
bats. During the winter months, the DSS offers daytime tours
to view the entrance. Persons interested in attending one of
these tours should make reservations through the Devil's Sinkhole
Society:
Devil's Sinkhole Society Inc.
101 Sweeten St.
P.O. Box 97
Rocksprings, Texas 78880
(830)-683-2287
DSS website for information on tours and local accommodations:
http://www.devilssinkholetx.com/information.html
The interior of the cave is accessible only for
scientific work and occasional caving trips by experienced vertical
cavers. TPWD has kept the cave closed due to concerns for
safety and bat conservation. Three people have died in the
sinkhole, the first around 1900, the second in 1960, and the most
recent in 1972. Caution and vertical competency are required
in and near the shaft at all times. Description:
The Devil's Sinkhole
is one of the premier caves of Texas and among the legendary classic pits
of the U.S. The cave is a immense 20-30 m diameter shaft that drops 42
m (138 ft.) into a room measuring more than 100 m in diameter.
The huge entrance to this National
Natural Landmark is somewhat obscure because it lies flat in a flat upland
of the Edwards Plateau-some people have nearly driven into it!
The shaft entrance is about 14 m in diameter and is sharply undercut to
a diameter of more than 25 m. About 34 m down the pit, it suddenly opens
into an immense room measuring 138 m long by 76 m wide. While many find
the sharp lip of the shaft tricky to negotiate, it provides a free-hanging
42 m rappel acclaimed as the finest in the state. The rappel ends on top
of a breakdown mountain located centrally in the room. The view from the
mountaintop is awesome; sunlight illuminates most of the vastness, which
extends to a depth of 80 m below the entrance. The room houses one of the
larger bat colonies in Texas, so the guano is pervasive and often deep,
sometimes hiding small holes or crevices in the breakdown floor. Along
the northwest and southwest corners of the room, breakdown has separated
some areas into smaller rooms, two of which lead deeper to water. These
"lake rooms" have been explored by divers to depths of 11 m without finding
any significant passages. The main Lake Room in the northwest corner of
the room is accented with speleothems. Historically, the Devil's Sinkhole
is best known for its impressive shaft entrance. Ranchers who discovered
the cave in 1876 thought is was "a helluva hole," but their more genteel
wives suggested "Devil's Sinkhole" as a less vulgar name. Graffiti carved
into rocks at the base of the pit indicates it was descended as early as
1889. Exploration of the cave has run the gamut of vertical technique and
technology, including massive wooden ladders, ladders of barbed wire with
stick rungs, sheep-wire fencing, winch-powered elevator, car-powered cables
connected to seat harnesses and bosun's chairs, prussik knots, cable ladders,
and modern single rope techniques. With Texas as the jumping off point
for expeditions to deep caves in Mexico, many modern vertical caving techniques
were first tried and tested at the Sinkhole. Over the years the Devil's Sinkhole
has been the subject of many expeditions, enterprises, and studies. From
the 1950s to the early 1980s, several unsuccessful attempts were made with
scuba, gravity meters, and well drilling in hopes of finding adjoining
rooms and passages. Films and videos were made in the cave in 1947 and
1989. From the first years of its discovery, the cave has been recognized
and used as a resource in many ways: cowboys lusted for honey from bee
hives that hung in the shaft; guano was mined intermittently from the cave
from at least the 1930s through the 1950s; windmill pipes were laid down
into the Lake Room to water-parched cattle; an elevator cage was installed
on a boom for a brief commercial period in 1949 and 1950 when visitors
could ride up and down the shaft for $1 (the cage can be found on the east
slope of the breakdown mountain); and during World War II the U.S. Government
sent two young soldiers into the cave to study the bats for possible use
in delivering incendiary bombs. The soldiers nearly died trying to climb
the rotten old wooden ladder, and had to be hoisted out on a rope.
In 1985, the Texas Parks and Wildlife Department purchased the
cave and surrounding 1860 acres from the Whitworth Estate and opened the area to
limited public access in 1992 as a State Natural Area. Since that time,
there has been little visitation within the cave due to liability concerns and
to preserve the cave's ecosystem. Since May 2002, the Devil's Sinkhole
Society (DSS), a group of volunteers working as concessionaires for the TPWD,
have organized guided tours to view the evening bat flights and daytime tours to
view the entrance. The DSS has a museum and gift shop at the Rocksprings
Visitors Center in downtown Rocksprings, Texas. In addition to the cave's famous pit
entrance, the Devil's Sinkhole is also well known for its large bat colony.
The colony seasonally varies from 30,000 to 1 million Mexican freetails
(Tadarida brasilien-sis mexicana), the ninth largest freetail colony
in Texas. Four other bat species have also been identified at the cave.
In 1958 the bat colony was estimated at 6 million. Like other Mexican free-tailed
bat colonies in Texas and the southwestern U.S., the sinkhole yields an
outstanding nightly spectacle as the cloud-like mass of bats spiral outward
for dinner. Their dive-bomb morning return is equally thrilling. While
the bats catch most of the attention, cave swallows and other birds also
share the pit, and the cave has a rich invertebrate fauna consisting mostly
of guanophiles. Troglobitic isopods, Cirolanides texensis, and an
endemic troglobitic species of amphipod, Stygobromus hadenoecus,
have been found in the lake rooms. Geologically, the Devil's Sinkhole
is simply a big room, the roof of which caved in to form the breakdown
mountain. The shaft and most of the room is within the Segovia Member of
the Edwards Limestone, while the lake rooms and sumps extend into the Fort
Terrett Member. The room formed under phreatic conditions by slow-moving
ground-water. As nearby valleys incised and groundwater levels dropped,
water drained out of the room. Without the water's buoyant support, the
ceiling began to collapse. Vadose water solutionally enlarged some fractures
and enhanced the collapse process; vadose seepage can still be seen trickling
down the walls of the main shaft. Although the cave's size is unusual,
seemingly isolated chambers of this sort are not unusual in the Edwards
Plateau region. Bibliography:
Byrd, T. 1983. The Devil's Sinkhole:
report of exploration, May 7-8, 1983. Unpublished report, 59 pp.
Couffer, J. 1992. Bat bomb, World
War II's Other Secret Weapon. Univ. Texas Press, Austin. 252 pp.
Elliott, W. R., and J.R. Reddell. 1975.
The fauna of the Devil's Sinkhole. Devil's Sinkhole area-headwaters
of the Nueces River. Austin, Univ. Texas at Austin. Division of Natural
Resources and Environment. :70-74. Fieseler, R. G., J. Jasek, and M. Jasek.
1978. An introduction to the caves of Texas. NSS Convention Guidebook,
No. 19, p. 93-94. Foster, F. 1950. The Devil's Sinkhole.
52-minute color and sound film. Video available for rental from the National
Speleological Society. Reddell, J. R., and A. R. Smith. 1965.
The caves of Edwards County. Texas Speleol. Surv., 2(5-6):19-28.
Texas Speleological Survey. 1991. Report
on the 60 longest and deepest caves. Texas Caver, 36(6):122.
Texas Parks and Wildlife Department.
1990. Down Under Texas. Video for Made in Texas television series.
VHS, 28 min. Available from the Department. Wahl, R. 1993. Important Mexican free-tailed
bat colonies in Texas. pp. 47-50 in Jorden, J. and R.K. Obele (eds.),
1989 Natl. Cave Mgmt. Symp. Proc. Texas Parks and Wildlife Press.
White, P. J. 1948. The Devil's Sinkhole.
Bull. Natl. Speleol. Soc., 10:214. |
