Tienkengs
National Geographic - Mystery Caves Of Guangxi
http://www.youtube.com/watch?v=wiYn-DeQjL8
A production of the National Geographic Channel in conjunction with Chinese
television CCTV-9
I have been asked to provide some clarification for the US caving community
about the use of the term "tiankeng". As many of you know, I have been leading
karst-focused tours for geologists and cavers and have first-hand knowledge of
Chinese karst since 1993. The cavers staring in the film have clearly had a
wonderful time in a spectacular area courtesy of National Geographic. The film
does a good job of explaining the area to the general public, and conveying the
wonder and excitement of exploring the karst of SW China.
This is a spectacular and interesting film. It is also contains some
unnecessary (in my opinion) exaggeration and self-promotion from National
Geographic. Anyone in the caving community who has been to the spectacular
karst areas of China recognizes the hyperbole. National Geographic seems either
to have done a poor research job (unlikely) or made a deliberate decision to
add additional "mystery" and danger to some of the most spectacular karst on
Earth. These are clearly world-class caves.
Cave scientists have understood how these huge pits are created for over a
hundred years. First described from the Dinaric Karst, known in China since
1992, explored in China by the Cave Research Expedition in 1993 (that was
before the Funny Word "tienkeng" had been coined), and explored extensively in
China by the Hong Meigui Cave Exploration Society (Erin Lynch) since 2001, the
British Cave Research Foundation , and others. These large limestone pits have
been found all over the world.
Simply, they are unusually large collapse dolines. They become large when there
is a good-sized underground river to keep extracting the breakdown blocks that
fall underground. In this part of China there is stratigraphically over 7 miles
(total thickness) of soluble limestone, high topographic relief, and it rains a
whole lot to produce the groundwater that dissolves the limestone. Fracture
traces in the limestone likely relate to the specific location of these pits,
just as they do for millions of other cave passages around the world.
The public perception and misunderstanding about tienkengs has been caused by
prominent Chinese geologist who arbitrarily made up the word "tienkeng" (Sky
Hole or Heavenly Pit) for exceptionally large collapse dolines. He defined them
as collapse dolines that are more than 100 wide and deep. This is a completely
arbitrary term. It is just like using the word "skyscraper" for tall buildings
and "megabuilding" for the very tallest one. Then you can claim that you city
has the only megabuilding in the world. It has allowed the Chinese to make a
Big Deal out of the fact that they do, indeed, have a lot (more than 50)
impressively gigantic collapse dolines in their country.
There are numerous references to these large pits in China that have been
written over the last 20 years, some accurate, some with included hyperbole.
Here is where to start:
Tiankengs: Definition and Description, 2006, Zhu Xuewen and Tony Waltham
http://www.speleogenesis.info/directory/karstbase/pdf/seka_pdf9541.pdf
This is a summary paper that concludes:
The concept of tiankeng karst has been considered within China as a term to
describe an extremely mature type of karst landscape that has matured beyond
normal fengcong karst with high relief. The term could be used to describe the
Leye karst in Guangxi, China, and perhaps the Nakanai karst in New Britain,
Papua New Guinea, both of which are distinguished by unusually large numbers of
tiankengs. However, some mature karst terrains contain just a few tiankengs,
notably just two in each of the karsts of Xingwen, Croatia and Mexico, and
these question the applicability of the term. Tiankeng karst may be purely
descriptive of the Leye and Nakanai terrains, but the term has not yet been
shown to have any geomorphological status with reference to karst evolution.
Also:
For a list of 33 "tienkengs" known to exist outside China in 2004 (including El
Sotano and Golindrinas in Mexico:
www.speleogenesis.info/directory/karstbase/pdf/seka_pdf9540.pdf
Special Issue: Tiankengs Transactions of the British Cave Research Association:
Cave and Karst Science: V. 32, n. 2&3 (in one volume). Descriptions of the
giant collapse dolines in China and the Wulong Karst World Heritage site.
Intro: http://www.speleogenesis.info/pdf/SG9/SG9_artId3289.pdf
The Mother Of All collapse Dolines is Xiaozhai, close to the Yangtzee River,
just south of the first of the Three Gorges. Down-cutting by the Yangtze has
created the great relief found in the area. Xiaozhai is 662 meters deep
(measured by the Chinese to obtain maximum depth) and has a trail (with many
steps) to the bottom, where a diversion tunnel for hydroelectric power has been
constructed. See The Yangtze Gorges Expedition : China caves project 1994 -
Guest Editorial by Andy Eavis, BCRA Cave and Karst Science Vol 22 (2) 1995.
Description of the Xiaozhai area south of Fungjie and the Yangtze Gorges.
So: It appears to me that the term "tienkeng" is proving itself to be a very
effective public relations term for the Chinese, similar to the effectiveness
of the term "spelunker" made up by Clay Perry in the 1940s and subsequently
used widely by newspaper reporters. The geologist and expedition leader does an
excellent job of explaining karst hydrology, even with the inclusion of
enhanced mystery, and of the previously well-known understanding of how these
giant pits developed. The whole tone of the movie (with enhanced mystery and
danger) is similar to the one National Geographic produced a couple of years
ago on what they claim to be the Biggest Cave in the World ( Hang Son Doong in
Vietnam: http://www.youtube.com/watch?v=aWaKRjTbZdI ), where he was also the
team geologist.
That said, this film is about some of the most spectacular karst in the world
and is worth watching. It WILL sell subscriptions.
DirtDoc
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