Thanks, Jerry.
It is not surprising that more big collapse dolines fitting the size definition of Prof. Zhu will be found on Earth. Remember that the size definition has nothing directly to do with origin and "tiankeng" is not a useful karst term (in my opinion) unless you are selling tourism or ego. But the term, like "spelunker", is going to be with us for quite a while. Your comments about rivers (or lack thereof) underneath the big collapse dolines in Mexico is interesting. There obviously had to be some process in the past to remove the huge volume of limestone to form the feature. Certainly the big ones that I have visited (including the father of them all, Škocjanske jame in Slovenia) all have a serious cave river beneath them to cart the stuff off. I have thought about Golindrinas and wondered about the mechanism there. Perhaps no one has gotten down below the bottom far enough to find the underlying stream passage. Perhaps the process of formation is a bit different and slower, and/or may not be active today. Size itself has nothing to do with how the thing formed. Size is descriptive only. Good science requires that you do not co-mingle description with genesis. That is why geologists separate the terms "gravel:" and "conglomerate" (descriptive) from "stream deposit" (genetic). That gives us something to figure out. Ain't Science Grand! DirtDoc ----- Original Message ----- From: "Jerry" <jerryat...@aol.com> To: dirt...@comcast.net, s...@caver.net, Texascavers@texascavers.com Sent: Wednesday, November 27, 2013 2:33:52 AM Subject: Re: [Texascavers] Tienkengs 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.
