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Length:
331.8 m (1,089 ft.)
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Vertical Extent:
28.8 m (94.5 ft.)
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Author:
George Veni
- Special Instructions:
Bat flight
viewing is available to the public in the evening for $5.
Directions:
Go 23 miles north from Brackettville on 624. Turn left at the Kickapoo
Caverns State Natural Area entrance left and drive down the dirt road west
1.1 mi. to a fence. The cave is on the hillside to the left, but visitors
may not visit the cave on their own. Continue to the park headquarters
for information about tours.
Description:
Stuart Cave
(formerly known as Green Cave - ref map) is a single, 332-m-long passage that
averages 20 m wide by 8 m high. It contains a world of guano and gnats.
The cave begins as a steep, slippery
ramp, leading down into a 17 m wide by 6 m high passage. Passage dimensions
begin to change almost immediately and vary throughout the length of the
cave; heights range from 1.8 to 14.6 m and widths from 7 to 18 m. The passage
is seldom less than huge. Much of the cave floor is covered with breakdown
and bat guano. Massive columns and other speleothems occur throughout the
cave, although most are stained and partially covered by guano. A decorated
and relatively guano-free alcove can be found about 80 m into the cave.
Some modest but clean stalactites occur in the room at the end of the cave.
Stuart Bat Cave has been known since the
19th century, but most visits were side trips from its more popular and
famous neighbor, Kickapoo Cavern. Consequently little historical information
has been recorded on this overshadowed cave. The cave was mined for guano
for many years up to at least 1957. Miners dug a shaft from the surface
into Stylolite Hall near the back of the cave. It was covered by the Texas
Parks and Wildlife Department (TPWD) in 1989 to return the cave to its
natural state and encourage growth of the bat colony. A few artifacts from
the mining remain in Stuart.
The cave's bat colony is mostly comprised
of the Mexican Free-tail Tadarida brasiliensis mexicana. Since TPWD's
covering of the shaft entrance the bat population has noticeably increased
and is estimated at 500,000. However, the present cover on the shaft is
temporary, and an air-tight cover is planned, which would increase the
cave's temperature making it more suitable for a maternity colony. Besides
the bats, other flying creatures which inhabit the cave include bees and
cave swallows (Hirundo fulva pallida) which nest near the entrance,
and several million gnats which swarm through the cave during the months
the bats are present. The invertebrate fauna has not been well investigated
but preliminary collections yield a typical array of guanophiles. The twilight
zone contains Rhadine howdeni, a fast-moving reddish, ant-like beetle.
Stuart Bat Cave
formed by slow-circulating phreatic groundwater which dissolved open large passages within the Devils
River Limestone. As the regional water table declined, water drained from
the cave, and its ceiling began to collapse into a more structurally stable
configuration. The only intact portion of phreatic passage is at the base
of the entrance ramp. The downcutting of surface valleys has twice intersected
the cave, once to form its entrance and once at its opposite end to block-off
further exploration. Although some of the cave's smaller speleothems are
relatively new, dating of the large speleothems indicate their most recent
deposits are about 256,000 years old, and most are older than 350,000 years.
The last big room in the cave, Stylolite Hall is named for a type of geologic
feature seldom seen in Texas caves. Stylolites are bedrock solution features
unrelated to the cave's development, which appear in place of bedding planes
as undulating to spiked lines. They are best seen in the northwest corner
of the room near the terminal breakdown.
Bibliography:
Smith, A. R., and J. R. Reddell. 1965.
The caves of Kinney County. Texas Speleol. Surv., 2(7):11,13,14.
Stuart, D. K. 1993. Personal communication.
Superintendent of Kickapoo Caverns and Devil's Sinkhole State Natural areas.
Veni, G. 1992. An introduction to the
age of Texas caves. Texas Caver, 37(5):82-83; reprinted in GEO²,
1992, 20(10):3-4 and cover.
Wahl, R. 1988. Personal communication.
Austin, Texas.
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