黑岩天坑
湘南地区唯一的天坑——黑岩天坑
说到天坑，大家可能首先想到的是重庆奉节的小寨天坑、广西乐业大石围天坑、贵州平塘打岔河天坑群、陕西汉中天坑群等。截止2016 年，岩溶地质研究方面公布的世界范围内有记录的天坑不超过80个，我国却有约50余个，但随着科考不断进行数据还在不断更新。
关于天坑在中国分布情况，中科院岩溶地质研究所张远海认为：我国的天坑主要集中在广西、云南、贵州、四川、重庆等南方地区，陕西汉中、东北地区也有出现。2001年之前一直将其作为喀斯特漏斗的特例，同年我国学者正式提议将这种独特的地质现象命名为“天坑”并被学界广泛认同使用至今。
Heiyan Tiankeng, the only Tiankeng in southern Hunan
When it comes to Tiankeng, you may first think of Xiaozhai Tiankeng in Fengjie, Chongqing, Dashiwei Tiankeng in Leye, Guangxi, Dachahe Tiankeng group in Pingtang, Guizhou, Hanzhong Tiankeng group in Shaanxi, etc. As of 2016 In, there were no more than 80 recorded tiankengs in the world published by karst geological research, but there were more than 50 in China. However, with the continuous scientific research, the data are still updated.
With regard to the distribution of Tiankeng in China, Zhang Yuanhai, Institute of karst geology, Chinese Academy of Sciences, believes that Tiankeng in China is mainly concentrated in southern regions such as Guangxi, Yunnan, Guizhou, Sichuan and Chongqing, and also in Hanzhong and northeast regions of Shaanxi. Before 2001, it has been regarded as a special case of karst funnel. In the same year, Chinese scholars officially proposed to name this unique geological phenomenon "Tiankeng", which has been widely recognized and used by the academic community.
天坑之父朱学稳认为，形成于碳酸盐岩中的喀斯特天坑，可分为两种基本类型：塌陷天坑和侵蚀天坑。塌陷型天坑，系指可溶性岩层中被溶蚀、侵蚀集中发生在某一地下深处，大量物质为强大的地下水动力系统 ( 主要是地下河 ) 所输出。在特定的地质与水文地质条件下，地下突发式或渐进式的崩塌及崩塌物被溶蚀、输出，作用持续不止，直至整个地下崩塌空间露出地表而形成 ；侵蚀性或冲蚀天坑，是地面的外源水在可溶性岩层的包气带中，从地表集中垂向冲蚀 ( 侵蚀 )与溶蚀形成的，其形成条件具有特定性和特殊性，故其分布甚是稀少。
When it comes to Tiankeng, you may first think of Xiaozhai Tiankeng in Fengjie, Chongqing, Dashiwei Tiankeng in Leye, Guangxi, Dachahe Tiankeng group in Pingtang, Guizhou, Hanzhong Tiankeng group in Shaanxi, etc. As of 2016 In, there were no more than 80 recorded tiankengs in the world published by karst geological research, but there were more than 50 in China. However, with the continuous scientific research, the data are still updated.
With regard to the distribution of Tiankeng in China, Zhang Yuanhai, Institute of karst geology, Chinese Academy of Sciences, believes that Tiankeng in China is mainly concentrated in southern regions such as Guangxi, Yunnan, Guizhou, Sichuan and Chongqing, and also in Hanzhong and northeast regions of Shaanxi. Before 2001, it has been regarded as a special case of karst funnel. In the same year, Chinese scholars officially proposed to name this unique geological phenomenon "Tiankeng", which has been widely recognized and used by the academic community.
万华岩的黑岩天坑是塌陷型天坑，属于罕见的岩溶地质遗迹，在目前的科考记录中是湘南地区唯一的天坑。
从地理位置看，万华岩位于五岭山脉骑田岭北麓，海拔只有240余米，域内的岩石是可溶蚀的石灰岩，属典型的喀斯特地貌。如果你对地理感兴趣，会发现五岭山脉的走向是一个奇特的存在，太平洋板块和欧洲板块的挤压、加上印度板块的挤压怎么看都不应该是如今的走向，这也成为学界的一大疑问。
巧合的是在万华岩西南方新田岭村称为“莲花洞”、“瓜棚下”、“ 宋家洞”、“礼家洞”等地方有流水侵入万华岩石灰岩岩体，不断溶蚀岩体，使洞腔不断扩大，根据中科院岩溶地质研究所的测定，这种侵蚀始于100—200万年前，现在这条地下河仍在对万华岩的岩体侵蚀下切，速率为0.19毫米∕年。
The black rock Tiankeng of wanhuayan is a collapse Tiankeng, which is a rare karst geological relic. It is the only Tiankeng in southern Hunan in the current scientific research records.
In terms of geographical location, Wanhua rock is located at the north foot of Qitianling mountain in Wuling mountain range, with an altitude of only more than 240 meters. The rocks in the region are soluble limestone, which belongs to typical karst landform. If you are interested in geography, you will find that the trend of Wuling mountains is a strange existence. The compression of the Pacific plate and the European plate, plus the compression of the Indian plate, should not be the current trend, which has also become a big question in the academic circles.
Coincidentally, XinTianLing village in the southwest of wanhuayan is called "Lotus cave" and "under melon shed"“ In songjiadong and Lijiadong, flowing water intrudes into the limestone mass of Wanhua rock, continuously dissolves the rock mass and expands the cavity. According to the measurement of Institute of karst geology, Chinese Academy of Sciences, this erosion began 1-2 million years ago, and now the underground river is still eroding and cutting down the rock mass of Wanhua rock at a rate of 0.19 mm / year.
匪夷所思的是，在距北洞口2245米处洞体上壁发生了塌陷，具体时间目前尚无科考报告，塌陷的块石被地下河不断溶蚀带走，大家可以想象一下：黑岩天坑开口直径100余米，深度130余米，坍塌的块石体量如此巨大，而水对崩塌下来的石灰岩块石溶蚀的速度大约是每年0.19毫米，黑岩天坑的形成需要多么漫长的时间啊！
如今，许多人慕名而来欣赏黑岩天坑的雄伟和壮观，感受刀劈斧削般的大型节理的震撼，更感受大自然惊心动魄超乎想象的伟力。
The black rock Tiankeng of wanhuayan is a collapse Tiankeng, which is a rare karst geological relic. It is the only Tiankeng in southern Hunan in the current scientific research records.
In terms of geographical location, Wanhua rock is located at the north foot of Qitianling mountain in Wuling mountain range, with an altitude of only more than 240 meters. The rocks in the region are soluble limestone, which belongs to typical karst landform. If you are interested in geography, you will find that the trend of Wuling mountains is a strange existence. The compression of the Pacific plate and the European plate, plus the compression of the Indian plate, should not be the current trend, which has also become a big question in the academic circles.
Coincidentally, XinTianLing village in the southwest of wanhuayan is called "Lotus cave" and "under melon shed"“ In songjiadong and Lijiadong, flowing water intrudes into the limestone mass of Wanhua rock, continuously dissolves the rock mass and expands the cavity. According to the measurement of Institute of karst geology, Chinese Academy of Sciences, this erosion began 1-2 million years ago, and now the underground river is still eroding and cutting down the rock mass of Wanhua rock at a rate of 0.19 mm / year.
