Thanks for the information, Dwight. For what it's worth, there are several more "tienkengs', as defined by Xuewen and Waltham (2006), in Mexico. I note that only two were recognized in the following references. I'm not sure it is worth informing anyone of this fact as tiankengs are really just large collapse dolines as you point out. Of interest is the fact that the majority of "tiankeng" features in Mexico do not have river systems at their base.
Jerry. -----Original Message----- From: dirtdoc <[email protected]> To: Cave NM <[email protected]>; Cave Texas <[email protected]> Sent: Tue, Nov 26, 2013 12:33 pm Subject: [Texascavers] Tienkengs Tienkengs National Geographic - Mystery Caves Of Guangxi http://www.youtube.com/watch?v=wiYn-DeQjL8 A production of the National Geographic Channel inconjunction with Chinese television CCTV-9 I have been asked to provide some clarification for theUS caving community about the use of the term "tiankeng". As many ofyou know, I have been leading karst-focused tours for geologists and cavers andhave first-hand knowledge of Chinese karst since 1993. The cavers staring in the film have clearlyhad a wonderful time in a spectacular area courtesy of NationalGeographic. The film does a good job ofexplaining the area to the general public, and conveying the wonder andexcitement of exploring the karst of SW China. This is a spectacular and interesting film. It is also contains some unnecessary (in myopinion) exaggeration and self-promotion from National Geographic. Anyone in the caving community who has beento the spectacular karst areas of China recognizes the hyperbole. National Geographic seems either to have donea poor research job (unlikely) or made a deliberate decision to add additional"mystery" and danger to some of the most spectacular karst on Earth. Theseare clearly world-class caves. Cave scientists have understood how these huge pits arecreated for over a hundred years. Firstdescribed from the Dinaric Karst, known in China since 1992, explored in Chinaby 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 CaveExploration Society (Erin Lynch) since 2001, the BritishCave ResearchFoundation, and others. These large limestone pits have been foundall over the world. Simply, they are unusually large collapse dolines. They become large when there is a good-sizedunderground river to keep extracting the breakdown blocks that fall underground. In this part of China there isstratigraphically over 7 miles (total thickness) of soluble limestone, hightopographic relief, and it rains a whole lot to produce the groundwater thatdissolves the limestone. Fracture traces in the limestone likely relate to thespecific location of these pits, just as they do for millions of other cavepassages around the world. The public perception and misunderstanding about tienkengshas been caused by prominent Chinese geologist who arbitrarily made up the word"tienkeng" (Sky Hole or Heavenly Pit) for exceptionally largecollapse dolines. He defined them ascollapse 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 thevery tallest one. Then you can claimthat you city has the only megabuilding in the world. It has allowed the Chinese to make a Big Dealout of the fact that they do, indeed, have a lot (more than 50) impressivelygigantic collapse dolines in their country. There are numerous references to these large pits inChina that have been written over the last 20 years, some accurate, some with includedhyperbole. Here is where to start: Tiankengs: Definition and Description, 2006, ZhuXuewen 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 hasbeen considered within China as a term to describe an extremely mature type ofkarst landscape that has matured beyond normal fengcong karst with high relief.The term could be used to describe the Leye karst in Guangxi, China, andperhaps the Nakanai karst in New Britain, Papua New Guinea, both of which aredistinguished by unusually large numbers of tiankengs. However, some maturekarst terrains contain just a few tiankengs, notably just two in each of thekarsts of Xingwen, Croatia and Mexico, and these question the applicability ofthe term. Tiankeng karst may be purely descriptive of the Leye and Nakanaiterrains, but the term has not yet been shown to have any geomorphologicalstatus with reference to karst evolution. Also: For a list of 33 "tienkengs"known to exist outside China in 2004 (including El Sotano and Golindrinas inMexico: www.speleogenesis.info/directory/karstbase/pdf/seka_pdf9540.pdf Special Issue: Tiankengs Transactions of the British Cave ResearchAssociation: Cave and Karst Science: V. 32, n. 2&3 (in one volume). Descriptions of the giant collapse dolines inChina 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 tothe Yangtzee River, just south of the first of the Three Gorges. Down-cutting by the Yangtze has created thegreat relief found in the area. Xiaozhai is 662 meters deep (measured by theChinese to obtain maximum depth) and has a trail (with many steps) to thebottom, where a diversion tunnel for hydroelectric power has been constructed. See TheYangtze Gorges Expedition: China caves project 1994 - Guest Editorial byAndy Eavis, BCRA Cave and Karst Science Vol 22 (2) 1995. Description of theXiaozhai 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 ClayPerry in the 1940s and subsequently used widely by newspaper reporters. The geologist and expedition leader does anexcellent job of explaining karst hydrology, even with the inclusion ofenhanced mystery, and of the previously well-known understanding of how these giantpits developed. The whole tone of themovie (with enhanced mystery and danger) is similar to the one NationalGeographic produced a couple of years ago on what they claim to be the BiggestCave in the World (Hang Son Doong inVietnam: http://www.youtube.com/watch?v=aWaKRjTbZdI), where he was also the team geologist. That said, this film is about some of the most spectacularkarst in the world and is worth watching. It WILL sell subscriptions. DirtDoc
